Recombinant human interferon-like proteins

ABSTRACT

This application relates to recombinant human interferon-like proteins. In one embodiment a recombinant protein created by gene shuffling technology is described having enhanced anti-viral and anti-proliferative activities in comparison to naturally occurring human interferon alpha 2b (HuIFN-α2b). The invention encompasses a polynucleotide encoding the protein and recombinant vectors and host cells comprising the polynucleotide. Preferably the polynucleotide is selected from the group of polynucleotides each having a sequence at least 93% identical to SEQ ID: No. 1 and the protein is selected from the group of proteins each having an amino acid sequence at least 85% identical to SEQ ID NO: 2. The proteins and compositions comprising the proteins can be used for treatment of conditions responsive to interferon therapy, such as viral diseases and cancer.

REFERENCE TO RELATED APPLICATION

This application is a national stage of PCT/CA2007/001123 filed on 22Jun. 2007,and claims the benefit of and is a continuation of U.S.non-provisional application serial No. 11/764,786 filed on 18 Jun. 2007,now U.S. Pat. No. 7,625,555.

FIELD OF THE INVENTION

This application relates to recombinant proteins having humaninterferon-like biological activities.

BACKGROUND

In this application the interferon (IFN) nomenclature published inNature (1) has been adopted.

Human interferons (HuIFNs), which were discovered by Isaacs andLindenmann in 1957 (2), are a well-known family of cytokines secreted bya large variety of eukaryotic cells upon exposure to various stimuli,such as viral infection or mitogen exposure. IFNs can elicit manychanges in cellular behavior, including effects on cellular growth anddifferentiation and modulation of the immune system (3-7). HuIFNs havebeen classified into six subgroups, namely IFN-α, IFN-β, IFN-γ. IFN-ω,IFN-ε and IFN-κ. HuIFN-α (leukocyte-derived interferon) is produced inhuman leukocyte cells and, together with minor amounts of HuIFN-β(fibroblast-derived interferon), in lymphoblastoid cells. HuIFNs havebeen further classified by their chemical and biological characteristicsinto two general categories, namely Type I and Type II. Type I consistsof the IFN-α and INF-β subgroups as well as the recently discoveredIFN-ω, IFN-ε and IFN-κ subgroups. Type II has only has one member: IFN-γ(immune interferon).

The different interferon subgroups have different structural andbiological characteristics. HuIFN-β is an N-linked glycoprotein (8, 9)which has been purified to homogeneity and characterized. It isheterogeneous in regard to size, presumably due to its carbohydratemoiety. However, there is only one human IFN-β gene, which encodes aprotein of 166 amino acids. IFN-β has low homology to IFN-α, sharingabout 30-40% identity.

In contrast to the singleness of the IFN-β gene, HuIFN-α is a subgroup,consisting of a multigene family of 14 genes in essence. Minor variantsmade of one or two amino acid differences account for the multiplealleles (10). Excluding the pseudogene IFNAP22, there are 13 genes,encoding 13 proteins. Each protein comprises 165-166 amino acids. Theprotein encoded by gene IFNA13 is identical to protein IFNA1. Thus thereare 12 individual interferon alpha proteins: IFNA1, IFNA2, IFNA4, IFNA5,IFNA6, IFNA7, IFNA8, IFNA10, IFNA14, IFNA16, IFNA17, and IFNA21. Aminoacid sequence identity among IFN-α subtypes has generally 80-85%homology (11).

Mature IFN-ω shows 60% nucleotide sequence homology to the family ofIFN-α species but is longer by 6 amino acids at its C-terminal. IFN-ω ismore distantly related to interferon-β (shares about 30% sequencehomology). Human IFN-ω is not classified in the IFN-α group because itis antigenically distinct from IFN-α and differs in its interaction withthe Type I IFN-α receptor (12). IFN-α is secreted by virus-infectedleukocytes as a major component of human leukocyte interferons.

The mature protein of human IFN-ε contains 185-amino acids, sharingabout 33% and 37% sequence homology to IFN-α2 and IFN-β respectively(13, 14). The function and biophysical properties of IFN-ε have not beencharacterized significantly in detail; however, it functions like Type Iinterferons. IFN-ε may also play a role in reproductive function (15).

IFN-κ, a 180 amino acid human cytokine, is a recently identified Type IIFN. The coding sequence of IFN-κ is ˜30% identical to the other Type Iinterferons found in humans. A distinguishing feature of IFN-κ is thedetectable constitutive expression of its transcript in uninduced cells,particularly keratinocytes. IFN-κ may play a role in the regulation ofsystemic or local immune functions through its effect on cells of theinnate immune system (16). However, IFN-κ exhibits low anti-viralactivity (17).

Human Type I interferon appears to bind to two-receptor subunits,IFNAR-1 and -2, which are widely distributed on the cell surface ofvarious cell types. Ligand involvement leads to the induction of thephosphorylation of tyrosine kinases TYK2 and JAK-1, which are coupled toIFNAR-1 and -2 respectively. Once phosphorylated, STAT proteins arereleased from the receptor and form homodimers as well as heterodimers(18, 19). Once released, the dimers of STATA associate with interferonResponsive Factor 9 (IRF-9), a DNA binding protein, forming a complexcalled IFN-stimulated gene factor-3 (ISGF-3), that migrates into thenucleus. Next, the ISGF-3 complex binds to a DNA element existing in theupstream of all IFN inducible genes. This is the so-called “classical”signal transduction pathway.

New modes of action and biochemical pathways regulated by Type I IFNsare continually being discovered. For example, downstream of PI3K in thesignal transduction pathway, nuclear factor kappa-B (NF-κB) and PKC-d,are associated with anti-apoptotic effects observed in neutrophilsincubated with IFN-β (20).

More than 300 genes, called interferon induced genes, are responsive tothe IFN treatment. The most studied IFN proteins are those withanti-viral properties. For example, the enzyme of the 2,5oligosynthetasefamily (OAS-1 and -2) catalyzes the synthesis of short oligoadenylates,which bind and activate RNAseL, an enzyme that cleaves viral andcellular RNAs, thus inhibiting protein synthesis. DsRNA-activatedprotein kinase (PKR) phosphorylates the translation initiation factoreIF2a, also resulting in the inhibition of viral and cellular proteinsyntheses. More recently, PKR was also was found to be required for theactivation of transcription factor NF-κB, a central actor ininflammatory cytokine induction, immune modulation, and apoptosis. Mx(myxovirus-resistance) proteins inhibit the replication of the RNAviruses by either preventing transport of viral particles within thecell, or transcription of viral RNA. RNA-specific adenosine deaminase(ADAR) converts adensine to inosine, thus causing hypermutation of viralRNA genomes (21).

HuIFNs possess a broad spectrum of biological activities includinganti-virus, anti-tumor, and immunoregulation functions. The clinicalpotentials of human interferons have been widely explored, and aresummarized below.

With respect to anti-tumor applications, HuIFNs may mediate anti-tumoreffects either indirectly by regulating immunomodulatory andanti-angiogenic responses or by directly affecting proliferation orcellular differentiation of tumor cells (22). Interferon therapy hasbeen used in the treatment of various leukemias (23), for instance,hairy cell leukemia (24), acute and chronic myeloid leukemia (25-27),osteosarcoma (28), basal cell carcinoma (29), glioma (30), renal cellcarcinoma (31), multiple myeloma (32), melanoma (33), Kaposi's sarcoma(23) and Hodgkin's disease (34). Combination therapy of IFN-α withcytarabine (ara-C), 5-FU, hydroxyura and IL-2 are well studied, mostlyshowing significantly better results than the HuIFN-α alone (3).Synergistic treatment of advanced cancer with a combination of HuIFNsand temozolomide has also been reported (35).

With respect to anti-virus applications, HuIFNs have been usedclinically for anti-viral therapy, for example, in the treatment of AIDS(36), viral hepatitis including chronic hepatitis B, hepatitis C (37,38), papilloma virus infection (39), herpes virus infection (40), viralencephalitis (41), and in the prophylaxis of rhinitis and respiratoryinfections (40).

HuIFNs have also been used clinically for anti-bacterial therapy (42),for example, aerosolized HuIFN-γ (43) and HuIFN-α have been used inpatients with multidrug-resistant pulmonary tuberculosis (44). HuIFN-γhas been used in the treatment of multidrug-resistant tuberculosis ofthe brain (45).

HuIFNs have also been used clinically for immunomodulation therapy, forexample, to prevent graft vs. host rejection, or to curtail theprogression of autoimmune diseases, such as multiple sclerosis (46, 47)and Sjogren's syndrome (48). IFN-β is approved by FDA in the UnitedStates for the treatment of multiple sclerosis. Recently it has beenreported that patients with multiple sclerosis have diminishedproduction of Type I interferons and interleukin-2 (49). In addition,immunomodulation therapy with HuIFN-α seems to be an effective therapyin chronic myeloid leukemia (CML) patients relapsing after born marrowtransplantation (50).

With regard to vaccine adjuvantation, HuIFNs has been used clinically asan adjuvant in the treatment of melanoma (51) and may also be used as anadjuvant or coadjuvant to enhance or simulate the immune response incases of prophylactic or therapeutic vaccination for many other diseases(52).

HuIFN-α2a was the first angiogenesis inhibitor to be used in clinicaltrials and was effective in children for the treatment oflife-threatening hemangiomas (53, 54). Another clinical indication isgiant-cell tumor of the bone. Kaban et al. reported the dramaticregression of a large, rapidly growing, recurrent giant-cell tumor ofthe mandible (55).

Although HuIFNs have many important clinical applications, they doexhibit significant side effects and other limitations. Most cytokines,including HuIFNs, have relatively short circulation half-lives sincethey are produced in vivo to act locally and transiently. Since they aretypically administered as systemic therapeutics, HuIFNs need to beadministered frequently and in relatively large doses. Frequentparenteral administrations are inconvenient and painful. Further, toxicside effects associated with HuIFNs administration are often so severethat some people cannot tolerate the treatment. These side effects areprobably associated with systemic administration of high dosages.Further, in clinical studies it has been found that some patientsproduce antibodies to rHuIFN, which neutralizes its biological activity(56).

Clearly, development of novel interferon proteins with enhanced potencyis urgently needed for numerous applications, e.g., anti-cancertherapies, as well as anti-viral, immunotherapy, anti-parasitic,anti-bacterial, or any medical condition or situation where increasedinterferon activity and/or reduced side effects is required. Overall, itis highly likely that HuIFNs will play a major role in the nextgeneration of novel anti-tumor and anti-viral therapies (10).

It is well know in the art that the most efficient means to improve thepharmaceutical properties of cytokine drugs is to mutate the cytokineprotein itself Various strategies and techniques to mutate interferonpeptides have evolved over time. Generally, three strategies arecurrently used to create HuIFN-α mutants.

The first strategy is to make IFN hybrids. Some researchers have takenadvantage of the presence of naturally occurring restrictionendonuclease (RE) cleavage sites within IFN-encoding sequences to piecetogether homologous coding fragments (57, 58). The production of anumber of hybrid IFNs has been reviewed by Horisberger and Di Marco(11); this article provides an overview of the process of constructionof such molecules. Specific examples of methods for the construction ofhybrid interferons are described. Some researchers have taken theadvantage of PCR amplification to construct mutant IFN-αs to therebycreate specifically-desired nucleic acid fragments and then gain thepotential of piecing together new pieces of different IFNs (59). U.S.Pat. No. 6,685,933 (60) also describes PCR amplification techniques tomake human IFN hybrids. The interferon hybrids may be created within aninterferon subgroup, such as described in U.S. Pat. Nos. 5,137,720 (61)and 6,685,933 (60) or among at least two different interferonclassification groups, such as described in U.S. Pat. Nos. 6,174,996(62) and 6,685,933 (60). In addition, the parent genes of the hybrid maycome from one species (mostly from human), for example, hybrids betweenHuIFN-α and HuIFN-ω, or from more than one animal species, for instance,hybrids between human and murine interferon-αs (63).

A second strategy to construct interferon mutants is to usesite-directed point mutagenesis by introducing changes of one or morenucleotides into IFN DNA molecules (64). Recently, systematic mutationand computational methods are used as a guide for protein mutagenesis(65).

A third strategy for the construction of Type I HuIFNs is to shuffle IFNgene fragments which are created by RE digestion, PCR amplification,chemically synthesis or DNase digestion, followed by PCR to randomlypiece the fragments together and then amplify them. The resulting PCRproducts are in fact a pool of rearranged interferon alpha genefragments which may be used to construct a DNA library, from which DNAclones with desired phenotypes may be isolated (66). For example, Changet al have described a method for constructing and screening a HuIFNshuffling library to identify HuIFN derivates with increased anti-viraland antiproliferation activities in mouse cells (67).

Human Interferon alfacon-1 (consensus interferon) is a recombinantnon-naturally occurring HuIFN-α with 166 amino acids. It has beengenerated by assessing the most highly conserved amino acids in eachcorresponding region based on the known cloned HuIFN-α sequences. It has89% sequence homology at amino acid level to HuIFN-α2b and a specificanti-viral activity of approximately 10⁹ IU/mg. Human Interferonalfacon-1 has approved for the treatment of chronic HCV infection inpatients 18 years or older with compensated liver disease (68).

Although some recombinant interferon proteins are known in the priorart, there is a need for new interferon-like proteins and proteincompositions having enhanced biological activities.

SUMMARY OF THE INVENTION

In accordance with the invention, an isolated polynucleotide encoding aprotein having human interferon-like biological activities is disclosed.In one embodiment the polynucleotide comprises a nucleotide sequence atleast 93% identical to SEQ ID No: 1. In other embodiments the nucleotidesequence is at least 95% identical or at least 98% identical to SEQ IDNo: 1.

In one embodiment, the invention comprises a protein selected from thegroup consisting of proteins each having an amino acid sequence at least85% identical to SEQ ID No: 2. Preferably the protein is non-naturallyoccurring and has enhanced anti-viral and anti-proliferative activity incomparison to human interferon alpha 2b (HuIFN-α2b). For example, theprotein may have anti-viral activity at least 2 fold greater thanHuIFN-α2b and anti-proliferative activity at least 10 fold greater thanHuIFN-α2b. In particular embodiments the protein amino acid sequence isat least 90% identical or at least 95% identical to SEQ ID No: 2

The invention encompasses recombinant vectors comprising the sequence ofthe polynucleotide and host cells containing the vectors. The inventionalso encompasses polypeptide fragments exhibiting human interferon-likebiological activities. The invention further includes protein constructsand other compositions exhibiting interferon-like biological activities,such as conjugates comprising the protein and another moiety, such as aninorganic polymer. The invention further includes methods and uses ofthe protein and the compositions for therapeutic purposes, for exampleas anti-viral or anti-cancer agents. The invention may be also be usedfor treatment of other conditions responsive to interferon therapy.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 depicts a complete DNA sequence encoding a novel protein of theinvention referred to herein as Novaferon™ (SEQ ID No:1) (A). FIG. 1also shows the predicted amino acid sequence of Novaferon (SEQ ID No:2)(B), and the alignment of the Novaferon amino acid sequence with theNovaferon DNA sequence (C). The first amino acid, cysteine, in themature Novaferon protein is designated as residue 1.

FIG. 2 shows nucleotide sequence alignment of the Novaferon gene withthe HuIFN-α14 gene (Genebank number: NM_(—)002172) (A) and amino acidsequence alignment of the Novaferon protein with the HuIFN-α14 protein(translated, Genebank number: NM_(—)002172) (B). The first amino acid,cysteine, in the mature Novaferon protein is designated as residue 1.Novaferon shares approximately 93% sequence identity (462/498) withHuIFN-α14 at the nucleotide level and approximately 87% sequenceidentity (144/166) at the amino acid level. Divergent nucleotides areindicated by a blank in the middle line.

FIG. 3 shows nucleotide sequence alignment of the Novaferon gene withthe HuIFN-α2b gene (Genebank number: NM_(—)000605) (A) and amino acidsequence alignment of the Novaferon protein with the HuIFN-α2b protein(translated from HuIFN-α2b gene with Genebank number: NM_(—)000605) (B).The first amino acid, cysteine, in the mature Novaferon protein isdesignated as residue 1. Novaferon shares approximately 89% sequenceidentity (445/498) with HuIFN-α2b at the nucleotide level andapproximately 81% sequence identity (135/166) at the amino acid level.Divergent nucleotides are indicated by a blank in the middle line.

FIG. 4 is a graph showing in vitro anti-proliferative inhibition ofDaudi cells by Novaferon in comparison with HuIFN-α2b.

FIG. 5 is a graph showing the in vivo anti-tumor effects of Novaferonand HuIFN-α2b in nude mice with human prostate cancer PC-3 xenografts.

FIG. 6 is a graph showing the in vivo anti-tumor effects of Novaferonand HuIFN-α2b in nude mice with human liver cancer Hep G2 xenografts.

FIG. 7 is a graph showing the in vivo anti-tumor effects of Novaferonand HuIFN-α2b in nude mice with human melanoma A-375 xenografts.

FIG. 8 is a graph showing the in vivo anti-tumor effects of Novaferonand HuIFN-α2b in nude mice with colon cancer LS 180 xenografts.

FIG. 9 is a graph showing the in vivo anti-tumor effects of Novaferonand HuIFN-α2b in nude mice with human leukemia HL 60(S) xenografts.

DETAILED DESCRIPTION

Throughout the following description, specific details are set forth inorder to provide a more thorough understanding of the invention.However, the invention may be practiced without these particulars. Inother instances, well-known elements have not been shown or described indetail to avoid unnecessarily obscuring the invention. Accordingly, thespecification and drawings are to be regarded in an illustrative, ratherthan a restrictive, sense.

Definition of Terms

Before describing the present invention in detail, it is to beunderstood that this invention is not limited to the particular proteinmolecules, methodology, protocols, cell lines, vectors, and reagentsdescribed as such may vary. It is also to be understood that theterminology used herein is for the purpose of describing particularembodiments only, and is not intended to limit the scope of the presentinvention which will be limited only by the appended claims.

In order to make the invention described herein more fully understood,the following terms are employed, and intended to be defined asindicated below. It is to be understood that the terminology used hereinis for the purpose of describing particular embodiments only, and is notintended to limit the scope of the present invention which will belimited only by the appended claims.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meanings as commonly understood by one of ordinary skillin the art to which this invention belongs. All publications mentionedherein are incorporated herein by reference for the purpose ofdescribing and disclosing the cell lines, vectors, and methodologieswhich are reported in the publications and which might be used inconnection with the invention. Nothing herein is to be construed as anadmission that the invention is not entitled to antedate suchdisclosures by virtue of prior invention.

The term “interferon” refers to a family of secreted proteins producedby a variety of eukaryotic cells upon exposure to various environmentalstimuli, including virus infection or exposure to a mitogen. In additionto having anti-viral properties, interferons have been shown to affect awide variety of cellular functions. All interferon units are expressedherein with reference to WHO international standards, 94/786 (rHuIFN-αconsensus) and 95/650 (rHuIFN-α2a).

The term “interferon-like” refers to functional and/or structuralfeatures exhibited by or similar to known interferons or interferonanalogues. For example, “interferon-like biological activities” includesanti-viral and anti-proliferative activities. Other examples ofinterferon-like biological activities are described herein and would beunderstood by a person skilled in the art. The plural term “activities”includes the singular term “activity”; that is, the inventionencompasses recombinant proteins or other protein constructs orcompositions which exhibit at least one interferon-like activity.

The term “consensus interferon” refers to a type of synthetic interferonhaving an amino acid sequence that is a rough average of the sequencesof all the known human alpha interferon sub-types. It has been reportedthat consensus interferon has a higher (about 5-fold) anti-viral,anti-proliferation and NK cell activation activity than any naturalhuman IFN-α subtype.

The term “isolated” as used herein refers to molecules, such as DNA orRNA, that have been removed from their native environment. For example,recombinant DNA molecules contained in a vector are considered isolatedfor the purposes of the present invention. Further examples of isolatedDNA molecules include recombinant DNA molecules maintained inheterologous host cells or purified (partially or substantially) DNAmolecules in solution. “Isolated” DNA also includes DNA moleculesrecovered from a library which may contain natural or artificial DNAfragments of interest, as well as chemically synthesized nucleic acids.Isolated nucleic acids may therefore be recombinantly produced.

The term “nucleotide sequence” refers to a sequence of nucleotidescomprising an oligonucleotide, polynucleotide or nucleic acid molecule,and fragments or portions thereof. In the case of a DNA molecule, thesequence may comprise a series of deoxyribonucleotides and in the caseof an RNA molecule the sequence may comprise a corresponding series ofribonucleotides. The oligonucleotide, polynucleotide or nucleic acidmolecule may be single- or double-stranded and the nucleotide sequencemay represent the sense or antisense strand.

The terms “oligonucleotide fragment” or a “polynucleotide fragment”,“portion,” or “segment” or “probe” or “primer” are used interchangeablyand refer to a sequence of nucleotide residues which are at least about5 nucleotides in length. Preferably the fragments can be used tohybridize to a target nucleotide sequence. A primer serves as aninitiation point for nucleotide polymerization catalyzed by either DNApolymerase, RNA polymerase or reverse transcriptase. A fragment orsegment may uniquely identify each polynucleotide sequence of thepresent invention. Preferably the fragment comprises a sequencesubstantially similar to SEQ ID NO: 1.

The terms “protein” or “peptide” or “oligopeptide” or “polypeptide referto naturally occurring or synthetic molecules comprising a sequence ofamino acids.

The term “open reading frame,” or ORF, means a series of nucleotidetriplets coding for amino acids without any termination codon andusually denotes a sequence translatable into a protein.

The term “mature protein coding sequence” refers to a sequence whichencodes a protein or peptide without a signal or leader sequence. Theprotein may have been produced by processing in the cell which removesany leader/signal sequence. The protein may be produced synthetically orby using a polynucleotide only encoding only the mature protein codingsequence.

The terms “purified” or “substantially purified” as used herein meansthat the indicated protein is present in the substantial absence ofother biological macromolecules, e.g., other proteins, polypeptides andthe like. The protein is purified such that it constitutes at least 95%by weight of the indicated biological macromolecules present (but water,buffers, and other small molecules, especially molecules having amolecular weight of less than 1000 daltons, can be present).

The term “recombinant expression vehicle or vector” refers to a plasmidor phage or virus or vector, for expressing a protein from a DNA (RNA)sequence. An expression vehicle can comprise a transcriptional unitcomprising an assembly of (1) a genetic element or elements having aregulatory role in gene expression, for example, promoters or enhancers,(2) a structural or coding sequence which is transcribed into mRNA andtranslated into protein, and (3) appropriate transcription initiationand termination sequences. Structural units intended for use in yeast oreukaryotic expression systems preferably include a leader sequenceenabling extracellular secretion of translated protein by a host cell.Alternatively, where recombinant protein is expressed without a leaderor transport sequence, it may include an amino terminal methionineresidue. This residue may or may not be subsequently cleaved from theexpressed recombinant protein to provide a final product.

The term “substantial similarity” refers to a nucleic acid or fragmentthereof which has a high degree of sequence identity with anothernucleic acid when optimally aligned with the other nucleic acid or itscomplementary strand. The sequence identity or homology may bedetermined using sequence analysis software, for example, BLASTN. Afirst nucleic acid is considered to be substantially similar to a secondnucleic acid if they show sequence identity of at least about 85-95% orgreater when optimally aligned. For example, to determine sequenceidentity or homology between two different nucleic acids, the BLASTNprogram “BLAST 2 sequences” is used. This program is available forpublic use from the National Center for Biotechnology Information (NCBI)over the Internet(http://http://www.ncbi.nlm.nih.gov/blastbl2seq/wblast2.cgi) (69). Byway of non-limiting example, such comparisons may be made using thesoftware set to default settings (expect=10, filter=default, open gap=5,extension gap=2 penalties, gap×dropoff=50). Likewise, a first protein orpolypeptide is considered to be substantially similar to a secondprotein or polypeptide if they show sequence identity of at least about85%-95% or greater when optimally aligned and compared using BLASTsoftware (blastp) using default settings.

By way of further illustration, a polynucleotide having a nucleotidesequence at least, for example, 95% “identical” to a referencenucleotide sequence encoding a protein, means that the nucleotidesequence of the polynucleotide is identical to the reference sequenceexcept that the polynucleotide sequence may include up to five pointmutations per each 100 nucleotides of the reference nucleotide sequenceencoding the protein. In other words, to obtain a polynucleotide havinga nucleotide sequence at least 95% identical to a reference nucleotidesequence, up to 5% of the nucleotides in the reference sequence may bedeleted or substituted with another nucleotide, or a number ofnucleotides up to 5% of the total nucleotides in the reference sequencemay be inserted into the reference sequence.

The terms “complementary” or “complementarity”, as used herein, refer tothe natural binding of polynucleotides under permissive salt andtemperature conditions by base-pairing. For example, the sequence“A-G-T” binds to the complementary sequence “T-C-A”. Complementaritybetween two single-stranded molecules may be “partial”, in which onlysome of the nucleic acids bind, or it may be complete when totalcomplementarity exists between the single stranded molecules. The degreeof complementarity between nucleic acid strands has significant effectson the efficiency and strength of hybridization between nucleic acidstrands. This is of particular importance in amplification reactions,which depend upon binding between nucleic acid strands.

The term “transformation” means introducing DNA into an organism so thatthe DNA is replicable, either as an extrachromosomal element, or bychromosomal integration. The term “transfection” refers to the taking upof an expression vector by a suitable host cell, whether or not anycoding sequences are in fact expressed.

The terms “treatment”, “treating” and grammatical equivalents thereof,are used in the broadest sense and include therapeutic treatment,prevention, prophylaxis and amelioration of certain undesired symptomsor conditions.

The terms “biologically activity” and “biological activities” as usedherein, refers to structural, regulatory, biochemical or otherbiological functions in living systems, for example similar or identicalto naturally or non-naturally occurring molecules.

The term “anti-proliferation” and “anti-proliferative” as used hereinrefers to slowing and/or preventing the growth and division of cells,resulting in the reduction of the total cell number and/or reduction thepercentage of the target cells in any one or all of the cell cyclephases. Cells may further be specified as being arrested in a particularcell cycle stage: G1 (Gap 1), S phase (DNA synthesis), G2 (Gap 2) or Mphase (mitosis). The term “anti-proliferative activity” as used hereinrefers to the activity of a protein, protein construct, or compositionwhich inhibits cell proliferation, especially neoplastic cellproliferative, e.g., cancer cells, either in vitro or in vivo.

The term “anti-tumor” or “anti-cancer” as used herein refers tocounteracting or preventing the formation of malignant tumors. The“anti-tumor activity” or “anti-cancer activity” when used herein refersto the activity of a protein, protein construct, or composition whichinhibits cell proliferation, especially neoplastic cell proliferation,e.g., of cancer cells, either in vitro or in vivo.

The term “IC₅₀”, or the “half maximal inhibitory concentration”,represents the concentration of an inhibitor, such as a protein, that isrequired for 50% inhibition of cell growth in vitro.

The terms “anti-viral” and “anti-virus” as used herein refers to slowingand/or preventing virus infection of cells or interfering with virusreplication in cells in vitro and/or in vivo, resulting in slowing orstopping of virus propagation, or reduction in the total number of virusparticles. The “anti-viral activity” as used herein means the activityof a protein, protein construct, or composition that inhibits viralinfections or interferes with viral replication, either in vitro and/orin vivo.

Novaferon Protein

The present invention relates to the preparation and characterization ofa novel human interferon-like protein, referred to herein as“Novaferon”™. As described in detail below, the Novaferon proteinexhibits enhanced anti-viral and anti-proliferative biologicalactivities in comparison to naturally occurring HuIFN-α2b as measured instandard in vitro tests. In particular, the Novaferon protein shows a12.5-fold increase in anti-viral activity when tested in a Wish-VSVsystem, and about a 400-fold improvement in anti-proliferativeinhibition of Daudi cell growth as compared to HuIFN-α2b in the sametesting systems.

In one embodiment, the Novaferon protein is encoded by a polynucleotideconsisting of 498 nucleotides as shown in SEQ ID No: 1 and FIG. 1(A).The mature Novaferon protein consists of 166 amino acids as shown in SEQID No: 2 and FIG. 1(B). The polynucleotide and amino acid sequences andvariants thereof which are encompassed by the invention are described infurther detail below.

For comparison purposes, the homology of Novaferon with naturallyoccurring HuIFNs was explored by the inventors. BLAST searches revealedthat Novaferon has the highest homology to HuIFN-α14 at both thenucleotide and amino acid levels. As shown in FIG. 2, the polynucleotidesequence (SEQ ID No: 1) encoding Novaferon has a homology ofapproximately 93% (462/498) to HuIFN-α14 and the amino acid sequence hasa homology of approximately 87% (144/166) to HuIFN-α14. In comparison toHuIFN-α2b, the most-widely used human interferon product, the homologyis approximately 89% at nucleotide level (445/498) and approximately 81%(135/166) at amino acid level, as shown in FIG. 3.

In regard to synthetic IFN alfacon-1 (consensus interferon), Novaferonhas approximately 91% sequence identity at the nucleotide level(453/498) and approximately 84% sequence identity at the amino acidlevel (140/166).

As described in detail in the experimental section below, thepolynucleotide sequence (SEQ ID No: 1) was selected from a DNA shufflinglibrary of Type I human interferon. Briefly, the Novaferon protein wasproduced by transfection of host cells with a recombinant vectorcontaining the complete polynucleotide sequence of SEQ ID No: 1. TheNovaferon protein contained in the supernatant of the host cell-line waspurified and shown to exhibit human interferon-like biologicalactivities, such as anti-viral and anti-proliferative functions.

Polynucleotide and Variants

The novel polynucleotide sequence/nucleic acid molecule of the presentinvention consists of 498 nucleotides as shown in FIG. 1 (SEQ ID No: 1).Using the information provided herein, such as the nucleotide sequence,a nucleic acid molecule of the present invention encoding a Novaferonprotein (SEQ ID No: 2) may be obtained by recombinant expression,chemical synthesis or by using other standard molecular biologyprocedures, such as those for DNA mutagenesis.

The invention, in addition to the isolated nucleic acid molecule (SEQ IDNo: 1), also includes DNA molecules having sequences which are differentfrom the DNA sequence disclosed in SEQ ID No: 1 but, due to thedegeneracy of the genetic code, still encode the same or substantiallythe same amino acid sequence of the Novaferon protein (SEQ ID No: 2).The genetic codes and species-specific codon preferences are well knownin the art. Thus, it would be routine for one skilled in the art togenerate the degenerate variants of DNA sequences different from the DNAsequence of SEQ ID No: 1, for instance, to optimize codon expression fora particular host (e.g., to change codons in the human mRNA to thosepreferred by a bacterial host such as E. coli).

The invention further provides an isolated nucleic acid molecule havingthe nucleotide sequence shown in FIG. 1 (SEQ ID No: 1), or a nucleicacid molecule having a sequence complementary to the nucleic acidsequence in SEQ ID No: 1. The present invention also providesinformation about and relates to the recombinant vectors, which includethe isolated nucleic acid molecules of the present invention, and tohost cells containing the recombinant vectors, as well as to the methodsof making such vectors and creating host cells that express theNovaferon protein, and using the host cells for the production ofNovaferon by recombinant techniques.

Based on the nucleic acid sequence of the present invention (SEQ IDNo:1, FIG. 1(A), the invention encompasses nucleic acid molecules whichare substantially similar thereto, such as nucleic acids having at leastabout 85-95% or greater sequence identity to SEQ ID No: 1 when optimallyaligned. For example, in one aspect nucleic acids having about 93%, 95%,96%, 97%, 98% or 99% sequence identity to the nucleotide sequence shownin SEQ ID No: 1 are within the scope of the invention, irrespective ofwhether they encode proteins or polypeptides having biologicalactivities similar to Novaferon (such activities include but are notlimited to enhanced anti-viral, anti-proliferative and anti-tumorfunctions in comparison with HuIFNs). Such nucleic acid molecules couldbe used, for example, as probes for the detection of mRNA in cellsalready transfected with a vector containing the nucleotide sequence ofthe present invention for the production of Novaferon. In another words,these nucleic acid sequences at least about 93%, 95%, 96%, 97%, 98% or99% identical to the sequence shown in SEQ ID No: 1 could be used asmarkers for determining the expression of the heterologous genes in ahost cell.

Further, the invention includes a polynucleotide comprising any portionof at least about 30 contiguous nucleotides, preferably at least about50 contiguous nucleotides, of SEQ ID No: 1.

More generally, this invention includes and covers the fragments of anyand all isolated nucleic acid molecules that are identical to thepartial sequence(s) of the nucleotide sequence shown in FIG. 1 (SEQ IDNo: 1). In one embodiment such fragments may be at least about 15nucleotides in length and are useful as diagnostic probes and primers asdiscussed herein. Furthermore, this invention includes and covers largerfragments that are about 50 nucleotides or longer in length.

In addition to the nucleic acid sequence disclosed in SEQ ID No: 1encoding the Novaferon protein, the present invention also includes butis not limited to nucleic acid sequences that encode the amino acidsequence of the complete Novaferon protein together with extra aminoacids/peptide(s)/polypeptide(s), for example an added secretory leadersequence.

Also included in the invention are the sequences of nucleic acids thathave the nucleic acid sequence disclosed in SEQ ID No: 1 as well asadditional, non-coding sequences, including, for example but notlimiting to, introns and non-coding 5′ and 3′ sequences, such as thetranscribed, non-translated sequences that play a role in transcription,mRNA processing (i.e. splicing and polyadenylation signals, ribosomebinding and stability of mRNA), and additional coding sequences whichencode additional amino acids with or without functionalities.

The present invention further relates to the variants of the nucleicacid molecules of the present invention (SEQ ID No: 1), which encodeportions, analogs or derivatives of the Novaferon protein. Variants maybe obtained by screening an interferon shuffling library or usingmutagenesis techniques or/and other known techniques described in theart.

As explained above, such variants may include those produced bynucleotide insertions, deletions or substitutions. The insertions,deletions or substitutions may involve one or more nucleotides. Thesemutations may occur at the 5′ or 3′ terminal positions of the referencenucleotide sequence or anywhere between those terminal positions,interspersed either individually among nucleotides in the referencesequence or in one or more contiguous groups within the referencesequence. Alterations may produce conservative or non-conservative aminoacid substitutions, deletions or additions. Especially preferred amongthese are silent substitutions, additions and/or deletions, which do notalter the properties and activities of the Novaferon protein or portionsthereof. Also especially preferred in this regard are conservativesubstitutions.

One aspect of the invention provides an isolated nucleic acid moleculecomprising a polynucleotide having a nucleotide sequence at least 93%identical, and more preferably at least about 95%, 96%, 97%, 98% or 99%identical to a polynucleotide selected from the group consisting of: (a)a nucleotide sequence encoding the Novaferon protein having the completeamino acid sequence in SEQ ID No: 2 (i.e., positions 1-166 of SEQ ID No:2); and (b) a nucleotide sequence encoding a biologically activefragment of the protein of (a); and (c) a nucleotide sequencecomplementary to any of the nucleotide sequences in (a) or (b) above.

Due to the degeneracy of the genetic code, one with ordinary skill inthe art will immediately recognize that a large number of the nucleicacid molecules having a sequence at least about 93%, 95%, 96%, 97%, 98%,or 99% identical to the nucleic acid sequence of the nucleic acidsequence shown in FIG. 1 (SEQ ID No: 1) will encode a protein havingactivity similar or identical to the Novaferon protein. In fact, sincedegenerate variants all encode the same protein, this will be clear tothe skilled artisan even without performing a comparison assay. It willbe further recognized in the art that, for such nucleic acid moleculesthat are not degenerate variants, a reasonable number will also encode aprotein having interferon-like biological activities. This is becausethe skilled artisan is fully aware of amino acid substitutions that areeither less likely or not likely to significantly affect proteinfunction (e.g., replacing one aliphatic amino acid with a secondaliphatic amino acid), as further described below. For example, guidanceconcerning how to make phenotypically silent amino acid substitutions isprovided by Bowie et al (70), wherein the authors indicate that manyproteins are tolerant of amino acid substitutions.

Protein and Polypeptide Variants and Constructs

The present invention encompasses the Novaferon protein of SEQ ID:2 andproteins or polypeptide variants which are substantially similarthereto, such as non-naturally occurring proteins having at least about85-95% or greater amino acid sequence identity to SEQ ID No: 2. Forexample, non-naturally occurring proteins having at least about 85%,90%, 95%, 96%, 97%, 98% or 99% sequence identity to the amino acidsequence shown in SEQ ID No: 2 are within the scope of the invention.Further, the Novaferon protein of the invention may be structurallymodified by fusing it to other proteins or protein fragments or othermolecules for the purpose of enhancing its functions and properties.Examples include but are not limited to fusing it to otherproteins/protein fragments to increase its expression or to furtherstabilize the Novaferon protein.

In one embodiment, the Novaferon-encoding nucleic acid sequence and/orNovaferon proteins of the invention may be labeled with a label otherthan the scaffold. “Labeled” herein means that a compound of the nucleicacid sequence (SEQ ID No: 1) or the Novaferon protein (SEQ ID No: 2) hasbeen attached with at least one element, isotope or other chemicals(labels) to enable the detection of the compound. In general, labelsfall into three classes: a) isotopic labels, which may be radioactive orheavy isotopes; b) immune labels, which may be antibodies or antigens;and c) colored or fluorescent dyes. The labels may be incorporated intothe compound at any position.

Once made, the Novaferon protein may also be covalently modified. Onetype of covalent modification includes treating the Novaferon proteinwith an organic derivatizing agent that is capable of reacting withselected side chains or the N- or C-terminal residues of the Novaferonprotein. Derivatization with bifunctional agents is useful, forinstance, for crosslinking the Novaferon protein to a water-insolublesupport matrix or surface for use in the purification of anti-Novaferonantibodies or screening assays. Commonly used crosslinking agentsinclude 1,1-bis(diazoacetyl)-2-phenylethane, glutaraldehyde,N-hydroxysuccinimide esters (for example, esters with 4-azidosalicylicacid), homobifunctional imidoesters including disuccinimidyl esters suchas 3,3′-dithiobis(succinimidylpropionate), bifunctional maleimides suchas bis-N-maleimido-1,8-octane and agents such asmethyl-3-[(p-azidophenyl)dithio]propioimidate.

Other modifications of the Novaferon protein include: deamidation ofglutaminyl and asparaginyl residues to the corresponding glutamyl andaspartyl residues, respectively; hydroxylation of proline and lysine;phosphorylation of hydroxyl groups of seryl or threonyl residues;methylation of the -amino groups of lysine, arginine, and histidine sidechains (71); acetylaffon of the N-terminal amine; and amidation of anyC-terminal carboxyl group.

Another type of covalent modification of the Novaferon protein of thepresent invention comprises altering the native glycosylation pattern ofthe protein. This may be achieved, for example, by (1) deleting and/oradding one or more carbohydrate moieties found in the native sequence ofthe Novaferon protein, or (2) adding and/or deleting one or moreglycosylation sites that do not exist in the native sequence of theNovaferon protein.

Addition of glycosylation sites to Novaferon protein may be accomplishedby altering the amino acid sequence of the Novaferon protein. Thealteration may be made, for example, by the addition of, or substitutionby, one or more serine or threonine residues to the native sequence ofthe Novaferon protein (for O-linked glycosylation sites). Thealternation of the amino acid sequence of the Novaferon protein could beachieved through changes at the DNA level, particularly by mutating theDNA sequence encoding the Novaferon protein at pre-selected nucleotidebases so that the altered codons would translate into the desired aminoacids.

Another means of increasing the numbers of carbohydrate moieties on theNovaferon protein is by chemical or enzymatic coupling of glycosides tothe protein. Such methods are described in the art, for example, asearly as 1981, Aplin J D and Wriston J C Jr. had described thepreparation, properties, and applications of carbohydrate conjugates ofproteins and lipids (72).

Removal of carbohydrate moieties presented on the Novaferon protein maybe accomplished chemically or enzymatically or by mutationalsubstitution of the codons that encode the amino acid residues thatserve as targets for glycosylation. Chemical deglycosylation techniquesare known in the art and described, for instance, by Edge A S et al.(73). Enzymatic cleavage of carbohydrate moieties on polypeptides can beachieved by the use of a variety of endo- and exo-glycosidases asdescribed by Thotakura et al (74).

Such derivatized constructs may include moieties improving thesolubility, absorption, permeability across the blood brain barrier,biological half life, etc. Such moieties or modifications of Novaferonprotein may alternatively eliminate or attenuate any possibleundesirable side effects of the protein and the like. Moieties capableof mediating such effects are disclosed, for example, in Remington: TheScience and Practice of Pharmacy. (75).

Another type of covalent modification of Novaferon comprises linking theNovaferon protein to one of a variety of non-proteinaceous polymers,e.g., polyethylene glycol, polypropylene glycol, or polyoxyalkylenes,for example in the manner set forth in U.S. Pat. Nos. 4,640,835 (76);4,496,689 (77); 4,791,192 (78) or 4,179,337 (79).

Further, the Novaferon protein of the present invention may also bemodified in a way to form chimeric molecules comprising a Novaferonprotein fused to another heterologous polypeptide or amino acidsequence. In one embodiment, such a chimeric molecule comprises a fusioncompound of a Novaferon protein with a tag polypeptide which provides anepitope to which an anti-tag antibody can selectively bind. The epitopetag is generally placed at the amino- or carboxyl-terminus of theNovaferon protein. The presence of such epitope-tagged forms of aNovaferon protein can be detected using an antibody against the tagpolypeptide. Also, provision of the epitope tag enables the Novaferonprotein to be readily purified by affinity purification using ananti-tag antibody or another type of affinity matrix that binds to theepitope tag. In an alternative embodiment, the chimeric molecule maycomprise a fusion compound of a Novaferon protein with an immunoglobulinor a particular region/fragment of an immunoglobulin. For example, toform a bivalent form of the chimeric molecule, the Novaferon proteincould be fused to the Fc region of an IgG molecule.

Various tag polypeptides and their respective antibodies are well knownin the art. Examples include poly-histidine (poly-his) orpoly-histidine-glycine (poly-his-gly) tags; the flu HA tag polypeptideand its antibody 12CA5 (80); the c-myc tag and the 8F9, 3C7, 6E10, G4,B7 and 9E10 antibodies thereto (81); and the Herpes Simplex virusglycoprotein D (gD) tag and its antibody (82). Other tag polypeptidesinclude the Flag-peptide (83); tubulin epitope peptide (84) and the T7gene 10 protein peptide tag (85).

Furthermore, the Novaferon protein of the present invention can beproduced by chemical synthetic procedures known to those of ordinaryskill in the art. For example, polypeptides up to about 80-90 amino acidresidues in length may be produced on a commercially available peptidesynthesizer model 433A (Applied Biosystems, Inc., Foster City, Calif.US). Moreover, the longer chemically synthesized peptides up to 120residues are also commercially available, for example, fromBio-synthesis, Inc. Lewisville, Tex. USA). Thus, as will be readilyappreciated, the full-length mature Novaferon protein can be producedsynthetically (for example, in fragments which may then be connectedtogether).

Therefore, the Novaferon protein of the present invention (SEQ ID No: 2)includes all the protein and polypeptide preparations and constructsthat have the same amino acid sequence disclosed in SEQ ID No: 2,despite whether these Novaferon proteins and protein derivatives areproduced by chemically-synthetic procedures, and/or by recombinanttechniques from prokaryotic or eukaryotic host cells or other cells andhosts, including but not limiting to bacterials, yeasts, plants, insectsand mammalian cells. Depending on the hosts employed in a recombinantproduction method, the proteins of the present invention may beglycosylated or non-glycosylated, pegylated or non-pegylated. Inaddition, proteins of the invention may also include an initial modifiedmethionine residue, in some cases as a result of host-mediatedprocesses. Thus, it is well known in the art that the N-terminalmethionine encoded by the translation initiation codon is generallyremoved, with high efficiency, from any proteins after translation inall eukaryotic cells. While the N-terminal methionine on most proteinsalso is efficiently removed in most prokaryotes, for some proteins thisprokaryotic removal process is inefficient, depending on the nature ofthe amino acid to which the N-terminal methionine is covalently linked.

Production

The present invention also relates to the recombinant vectors whichconsist of the isolated DNA molecules of the present invention, to hostcells which are genetically engineered/transfected with the recombinantvectors, and to the production of the Novaferon protein or fragmentsthereof by recombinant techniques. The vector may be, for example, aplasmid, phage, viral or retroviral vector. Retroviral vectors may bereplication competent or replication defective. In the latter case,viral propagation generally will occur only in complementing host cells.Examples describing in detail the production of Novaferon are set forthbelow.

Preferred vectors for the expression of the Novaferon protein of thepresent invention include, but are not limited to, vectors comprisingcis-acting control regions effective for expression in a hostoperatively linked to the polynucleotide to be expressed. Appropriatetrans-acting factors are supplied either by the host, by a complementingvector or by the vector itself upon introduction into the host.

The nucleic acid sequence disclosed in present invention (SEQ ID No: 1)may be operatively linked to an appropriate promoter. “Promoter” hereinmeans any nucleic acid sequences capable of binding RNA polymerase andinitiating an extron (usually at the downstream (3′)) transcription ofthe coding sequence for the Novaferon protein into mRNA. A bacterialpromoter has a transcription initiation region which is usually placedproximal to the 5′ end of the coding sequence. This transcriptioninitiation region typically includes an RNA polymerase binding site anda transcription initiation site. Sequences encoding metabolic pathwayenzymes provide particularly useful promoter sequences. Examples includepromoter sequences derived from sugar metabolizing enzymes, such asgalactose, lactose and maltose, and sequences derived from biosyntheticenzymes such as tryptophan. Promoters from bacteriophage may also beused and are known in the art. In addition, synthetic promoters andhybrid promoters are also useful; for example, the tac promoter is ahybrid of the trp and lac promoter sequences. Furthermore, a bacterialpromoter can include naturally occurring promoters of non-bacterialorigin that have the ability to bind bacterial RNA polymerase andinitiate transcription. The preferred bacteria promoters include, butare not limited to, E. coli laci, trp, phoA and lacZ promoters, the T3and T7 promoters, the gpt promoter, the lambda PR, PL promoters and thetrp promoter

Eukaryotic promoters have a transcription initiating region, which isusually placed proximal to the 5′ end of the coding sequence, and a TATAbox, usually located 25-30 base pairs (bp) upstream of the transcriptioninitiation site. The TATA box is thought to direct RNA polymerase II tobegin RNA synthesis at the correct site. A mammalian promoter alsocontains an upstream promoter element (enhancer element), typicallylocated within 100 to 200 base pairs upstream of the TATA box. Anupstream promoter element determines the rate at which transcription isinitiated and can act in either orientation. Of particular use asmammalian promoters are the promoters from mammalian viral genes, sincethe viral genes are often highly expressed and have a broad host range.Examples include the SV40 early promoter, mouse mammary tumor virus LTRpromoter. Preferred animal cell promoters include, but are not limitedto, adenovirus major late promoter, herpes simplex virus promoter, andthe CMV promoter. Among known eukaryotic promoters suitable in thisregard are the CMV immediate early promoter, the elongation factor 1alpha (EF1A) promoter, the HSV thymidine kinase promoter, the early andlate SV40 promoters, and the promoters of retroviral LTRs, such as thoseof the Rous sarcoma virus (“RSV”). Preferred promoter sequences forexpression in yeast include the inducible GAL1/10 promoter, thepromoters from alcohol dehydrogenase, enolase, glucokinase,glucose-6-phosphate isomerase, glyceraldehyde-3-phosphate-dehydrogenase,hexokinase, phosphofructokinase, 3-phosphoglycerate mutase, pyruvatekinase, and the acid phosphatase gene.

Vectors for propagation and expression also generally include one ormore selectable markers. Such markers may be suitable for amplificationor the vectors may contain additional markers for this purpose. In thisregard, the expression vectors preferably contain one or more selectablemarker genes to provide a phenotypic trait for the selection of thetransfected host cells, although those skilled in the art will recognizethat certain system-selectable markers may be provided on separatevectors. Preferred markers include, for example, ampicillin (Amp),tetracycline (Tet) or hygromycin (HYG) resistance genes for culturing inE. coli and other bacterial. Yeast-selectable markers include ADE2,HIS4, LEU2, TRP1, and ALG7, which confer resistance to tunicamycin; theneomycin phosphotransferase gene, which confers resistance to G418; andthe CUP1 gene, which allows yeast to grow in the presence of copperions. Animal cell-selectable makers include dihydrofolate reductase(DHFR) gene, neomycin (Neo) or hygromycin (HYG) resistance genes.

Further, vectors for propagation and expression commonly contain one ormore sites for transcription initiation, termination and, in thetranscribed region, a ribosome binding site for translation. The codingportion of the transcripts expressed by the constructs preferablyincludes a translation initiating codon at the beginning and atermination codon (UAA, UGA or UAG) appropriately positioned at the endof the DNA sequence to be translated. Selection of promoters,terminators, selectable markers, vectors and other elements is a matterof routine design within the level of ordinary skill in the art. Manysuch elements are described in the literature and are available throughcommercial suppliers.

The following vectors are commercially available, and are preferred foruse in bacterias: pBV220 (86) and its derivates from Shanghai Sangon;pQE series from Qiagen; pET vectors from Qiagen; pBS vectors,Phagescript vectors, Bluescript vectors, pNH8A, pNH16a, pNH18A, pNH46Afrom Stratagene; and ptrc99a, pKK223-3, pKK233-3, pDR540, pRIT5 fromPharmacia. Among preferred eukaryotic vectors are pCI vectors fromPromega, pcDNA vectors from Invitrogen, pSV2CAT, pOG44, pXT1 and pSGfrom Stratagene; and pSVK3, pBPV, pMSG and pSVL from Pharmacia. Thesevectors are listed solely as examples to demonstrate that manycommercially available and well known vectors are available to those ofskill in the art for use in the production of the Novaferon proteindisclosed in the present invention by genetic/recombinant methods.

In certain preferred embodiments in this regard, the vectors providemeans for specific expression. Such specific expression may be inducibleexpression or expression only in certain types of cells or may be bothinducible and cell-specific. Particularly preferred among induciblevectors are vectors that can be induced to express by environmentalfactors that are easy to manipulate, such as temperature and nutrientadditives. A variety of vectors suitable for this application, includingconstitutive and inducible expression vectors for use in prokaryotic andeukaryotic hosts, are well known and employed routinely by those ofskill in the art.

The vector containing the DNA sequence disclosed in SEQ ID No: 1, forinstance, as well as an appropriate promoter, and other appropriatecontrol sequences, may be introduced, using a variety of art-knowntechniques, into an appropriate host cell suitable for the expression ofa desired protein. Representatives of such suitable hosts includebacterial cells, such as E. coli, Bacillus subtilis, Streptomyces cells;yeast cells, such as Pichia pastoris cells; insect cells, such asDrosophila S2 and Spodoptera Sf9 cells; mammalian cells such as CHO andCOS; and plant cells. Hosts for a great variety of expression constructsare well known, and those of skill art will be able, with theinformation disclosed in the present invention, to readily select a hostfor expressing the Novaferon protein disclosed in SEQ ID No: 2.

Host cells can be genetically engineered to incorporateNovaferon-encoding polynucleotides and express Novaferon proteins of thepresent invention. For instance, Novaferon-encoding polynucleotides maybe introduced into host cells using art-known techniques oftransfection. Such methods are described in many standard laboratorymanuals, such as those discussed by Kingston (87). Novaferon-encodingpolynucleotides may be introduced/transfected alone or with otherpolynucleotides. Such other polynucleotides may be introducedindependently, co-introduced or introduced jointly with theNovaferon-encoding polynucleotides disclosed in SEQ ID No: 1.

For example, Novaferon-encoding polynucleotides of the invention may betransfected into host cells together with a separate polynucleotideencoding a selectable marker for co-transfection and selection of themarker in mammalian cells. Alternatively, the Novaferon-encodingpolynucleotides may be incorporated into a vector containing aselectable marker-encoding DNA sequence for inducing propagation in thehost cells.

The engineered host cells transfected with the vectors containing theNovaferon-encoding polynucleotide can be cultured in conventionalnutrient media which may be modified specifically for activatingpromoters, selecting transformants or amplifying the target genes.Culturing conditions such as temperature, pH, etc. are adjusted andsuitable for the selected host cells to express the Novaferon protein ofthe present invention.

Suitable secretion signals may be incorporated and co-expressed with theNovaferon protein for promoting the secretion of the translated proteinpolypeptide into the lumen of the endoplasmic reticulum, into theperiplasmic space or into the extracellular environment.

Purification

A suitable host cell type is usually selected for the expression of thetarget recombinant protein, depending on the nature of the targetprotein and consideration of other conditions, such as the productioncosts, whether to scale up easily, size of industrial production, etc.The clones of the transfected cells that express the target protein withthe highest yield are then selected, and the final clone with theoptimal expression is named the target protein-expressing cell line andused for the production of the target protein. The cell line expressingthe target protein is grown in a medium containing various nutrients.For optimal growth of the cells and/or optimal expression of the targetprotein, various agents or conditions are used to induce the selectivepromoter incorporated with the cDNA sequence of the target protein inthe transfected vector. If the host cell type/expression system isbacteria, the cultured cells are harvested from the medium, typically bycentrifugation. The bodies of the harvested cells are broken by physicalor chemical means, and the harvested crude extracts, which contain thesynthesized target protein, are retained for further purification of theprotein. The methods applied to the disruption of the microbial cellsinclude but are not limited to freeze-thaw cycling, sonication,mechanical disruption, or use of cell lysing agents. Such methods arewell known to those skilled in the art.

The inventors used the bacteria. E. coli, as the host cell for theexpression of recombinant Novaferon protein. As described below, E.coli. was transfected with the vector that contained theNovaferon-encoding polynucleotide sequence, and one strain of E. coli.that had the optimal expression of the Novaferon protein was selectedfor the production of Novaferon protein. Once synthesized, the proteinmay be retained in the cytoplasm as insoluble granules, or may besecreted into the cytoplasm in soluble form. In the former case, thegranules are recovered after the lysis of the cell bodies, and denaturedusing, for example, guanidine isothiocyanate or urea. The re-folding ofthe denatured polypeptide/Novaferon protein is then obtained by dilutingthe denaturant with excessive dilute solution or by dialysis against asolution of urea and a combination of reduced and oxidized glutathione,followed by dialysis against a buffered saline solution. In the lattercase, the protein can be directly recovered, without denature, from theperiplasmic space in the soluble and functional form following thedisruption of the harvested cells. By avoiding the denaturing andre-folding procedures, the soluble Novaferon protein is not damaged andcontains no deformed or mis-folded protein molecules.

The inventors found that a significant portion of the synthesizedNovaferon protein produced in the E. coli cell line was secreted intothe cytoplasm. This portion was then purified as described below.

Activity Assays and Medical Uses

As indicated above, the Novaferon protein shows sequence homology tomany members of the interferon family, in particular to the interferonprotein translated by the mRNA of HuIFN-α14 (FIG. 2). HuIFN-α has beenshown to have a wide range of biological activities includinganti-viral, anti-proliferative, and immunomodulation activities (10).

With such homology to HuIFN-α, Novaferon would be expected to exhibitsimilar biological functions as HuIFN-α, including but not limiting to,the inhibition of tumor proliferation, anti-viral activities, NK cellactivation, and immune system modulation. Of particular importance isnot only the retaining of the HuIFN-α-like functional properties butalso the enhanced potency of these biological functions of the Novaferonprotein in comparison with HuIFN-α. To verify and determine the potencyof its functional properties, the biological activities of Novaferonprotein were thus determined using the classic and routine in vitroassays designed to detect the anti-viral and anti-proliferativeproperties. As described in the experimental section below, the in vivopotency of anti-proliferative properties of the Novaferon protein wasfurther observed in animal models of various human cancer types andcompared to HuIFN-α as well as to a chemical anti-cancer agent in someexperiments.

Many suitable assays for determining the activities of HuIFN are wellknown in the art. The inventors employed the in vitro cell-based assaysystems to determine the anti-viral and anti-proliferative activities.The same in vitro assays were used for all the procedures andexperiments related to the present invention, which included but notlimited to screening the human Type I interferon gene shuffling library,selecting Novaferon from the expressed proteins of the human Type Iinterferon gene shuffling library, and the determination of thebiological activities of the pure recombinant Novaferon protein.

There are many assays that measure the anti-viral activities of thetesting samples/agents by observing the degree of resistance of cells toviruses (88). Three principal bioassays have been used for measuring theanti-viral activities of HuIFN and their hybrids. They are classifiedaccording to the methods of determining the various aspects of virus oncultured cells.

The assay for determining the inhibition of virus-induced cytopathiceffects measures the degree of reduction of virus-induced lyticcytopathic effects on the cultured cells with pre-treatment of IFN. Thisassay can be performed in 96-well plates (89), and has been widely usedfor recombinant HuIFN-α since it provides a simple method for screeninga large number of samples.

The inhibition of virus plaque formation is another method ofquantifying the anti-viral activities of HuIFN in tissue cultures. Theresults of a plaque-reduction assay are independent of the multiplicityof infection. Moreover, a 50% reduction in plaque formation ismeasurable with high precision. Using the ubiquitous vesicularstomatitis virus (VSV) to induce the plaque formation, for instance, itcould determine the profile of cross-species activity of a particularrecombinant IFN by screening a number of cell lines from differentanimal species (90).

The third assay is based on the determination of the reduction of virusyield. Virus production is measured, usually during a single cell growthcycle, by the amount of virus released. This assay is particularlyuseful for testing the anti-viral activities of IFN against viruses thatdo not cause cytopathic effects, or that do not build plaques intarget-cell cultures. In this test, however, the multiplicity ofinfection affects the apparent degree of protection induced by a fixedconcentration of IFN (91).

The anti-viral activities of Novaferon were measured by a standardcytopathic effect-inhibition assay using WISH cells and vesicularstomatitis virus (VSV). Anti-viral activities were determined andcalibrated by using the standard reference samples of WHO internationalstandards: 95/650 (rHuIFN-α2a) and 94/786 (rHuIFN-α consensus). One unitof anti-viral activity is defined as the amount of protein needed toachieve 50% inhibition of the cytopathic effects of VSV on culturedcells. As described further below, the activity of Novaferon protein was2.5×10⁹ IU/mg, which is about 12.5-fold greater than that of HuIFN-α2b.These tests demonstrate that the anti-viral properties of Novaferon aregreatly enhanced in comparison to HuIFN-α2b. This increased potencyagainst virus, exhibited by Novaferon protein, provides the basis for apredicting enhanced anti-virus effects in vivo in humans. Based on thenature of HuIFNs, it is reasonable to expect a very broad anti-virusprofile for Novaferon. In another words, Novaferon should be more potenttoward a wide range of viruses than natural HuIFNs. The increasedanti-virus potency of Novaferon could be translated into betteranti-virus effects or better therapeutic effects in clinical setting forpatients with various viral diseases.

As explained above, IFNs also inhibit cell proliferation and exhibitpotent anti-tumor effects through a variety of mechanisms. Several invitro anti-proliferation tests have been established by using cellculture systems, and are well described in the art. Cell proliferationin these assays can be measured by counting cell numbers; crystal violetbioassay (92, 93); chemosensitivity to neutral red dye (94˜96);incorporation of radiolabelled nucleotides (97); incorporation of5-bromo-2′-deoxyuridine (BrdU) in the DNA of proliferating cells (98);use of tetrazolium salts (99, 100).

The human lymphoblastoid Daudi cell line is very sensitive to theanti-proliferation effect of HuIFN-α, and its growth in suspensioncultures facilitates the quantification of its cell numbers (101). Thiscell line has been used for measuring the anti-proliferation activity ofHuIFN-α and hybrids for many years (102). Other cell lines are also usedfor testing the anti-proliferation activity of a testing agent.

The anti-proliferative activities of Novaferon protein were observed invivo by observing the inhibition of the tumor mass growth by Novaferonadministration to animal models with various human tumor xenografts. Thein vivo anti-tumor effects of Novaferon was compared with HuIFN-α2b andin some xenograft models, with chemical anti-tumor agent as well.

As described in detail below, the inventors found that the in vitroanti-proliferative activity of Novaferon, measured by using standardDaudi cell method, was 400-fold more potent than natural HuIFN-α2b,which exhibits probably the most potent anti-proliferative activitiesamong all natural HuIFNs. The increased anti-proliferative potency ofNovaferon was broad and universal, as it exhibited more potent orenhanced inhibition, than natural HuIFN-α2b, of all the human cancercell lines the inventors tested in vitro. This indicates that the potentinhibition of human cancer by Novaferon is not selective. Although theextent of its enhanced anti-proliferative activities toward all thetested types of human cancer cell lines varied, Novaferon has thepotential to be a broad anti-cancer agent in clinical setting. This is asignificant advantage over chemical anti-cancer agents, monoclonalantibodies and other target-specific anti-cancer agents.

The xenograft animal model experiments described below further establishthat:

-   -   (1). The in vivo anti-proliferation effects of Novaferon were        greatly enhanced or more potent in comparison to natural        HuIFN-α2b    -   (2). The in vivo anti-proliferation effects of Novaferon, at        much lower doses, were better than the tested chemical agent,        5-Fluorouracil (5-FU) in the same xenograft model.    -   (3). Novaferon was able to achieve over 90% inhibition of cancer        growth in the xenograft models, but did not induce weight loss,        activity changes and other negative side-effects in the treated        animals, which was in sharp contrast to the significant weight        loss and activity reduction in the 5-FU-treated animals.

These results indicate that the in vitro and in vivo anti-proliferativeproperties of Novaferon are greatly enhanced, comparing to naturalHuIFN-α2b. The increased anti-proliferative potency of Novaferon istranslated into effective inhibition (>90%) of human tumor growth in amouse animal model, and this inhibition seems to work very broadly toall the types of human cancers tested and better than the classicchemical anti-cancer agent, 5FU. These results also indicate that thepotent inhibition of cancer cell growth by Novaferon is very specifictoward the cancer cell but not toward the normal cells as supported bythe observation of normal eating and activity behavior and no weightloss in Novaferon-treated animals. Novaferon thus has the potential towork on all or majority of human cancers.

In a preferred embodiment, the complete or partial molecule (s) ofNovaferon protein (SEQ ID No: 2), made by recombinant technologies usingthe polynucleotide sequence of SEQ ID No. 1 or chemically synthesized,could be applied to the treatment and/or prevention of any and/or all ofthe tumors and cancers of human-origin or non-human-origin, in humansand/or non-human species. These tumors, for example, include but are notlimited to, osteogenic sarcoma; multiple myeloma; Hodgkin's disease;nodular, poorly differentiated lymphoma; acute lymphocytic leukemia;acute myeloid leukemia; breast carcinoma; melanoma; papilloma; andnasopharyngeal carcinoma, colon cancer, liver cancer and melanoma.

In another embodiment, the complete or partial molecule (s) of Novaferonprotein (SEQ ID No: 2), made by recombinant technologies usingpolynucleotide sequence of SEQ ID No: 1 or chemically synthesized, couldbe applied to the treatment and/or prevention of any and/or all of theviral diseases in humans and/or non-human species. Examples of thesusceptible viral infections include, but are not limited to, viralencephalomyocarditis, influenza and other respiratory tract viralinfections, rabies and other viral zoonoses, and arbovirus infections,as well as herpes simplex keratitis, acute hemorrhagic conjunctivitis,varicella zoster, and hepatitis B and C, SARS and bird flu, human immunedeficiency syndrome (AIDS, HIV).

In another embodiment, the complete or partial molecule (s) of Novaferonprotein (SEQ ID No: 2), made by recombinant technologies usingpolynucleotide sequence of SEQ ID No: 1 or chemically synthesized, couldbe applied to the treatment and/or prevention of any and/or all of theimmune system-related disorders in humans. Examples of the immunedisorders include but are not limited to rheumatic arthritis, multiplesclerosis, and Sjogren's syndrome diabetes. The Novaferon protein mayalso be applied to preventing graft vs. host rejection as well.

In another embodiment, the complete or partial molecule (s) of Novaferonprotein (SEQ ID No: 2), made by recombinant technologies usingpolynucleotide sequence of SEQ ID No: 1 or chemically synthesized, couldbe applied to the treatment and/or prevention, as an immunoadjuvant, forany and/or all of the angiogenesis diseases. Example of the angiogenesisdiseases include but are not limited to hemangiomas, tumor-inducedneovasculature, age-related macular degeneration and diabeticretinopathy.

The Novaferon protein, alone or together with any other proteins/carriermaterials or other constructs, may be administered to humans and/ornon-human species in any pharmaceutically acceptablepreparations/formulations in any administration/deliverypathways/methods, which include but are not limited to the oral intake,inhalation, intranasal spray, intraperitoneal, intravenous,intramuscular, intralesional, or subcutaneous injection.

Pharmaceutical preparations/formulations containing the Novaferonprotein as the active ingredient could be made by incorporating anappropriate solid or liquid carrier, in the forms of liquid, solid,semi-solid, and/or any other clinically acceptable forms, such astablets, pills, powders, liquid solutions or suspensions, liposomes,suppositories, injectable, and infusible solutions. TheNovaferon-containing preparations/formulations could be made by usingthe conventional carriers, materials, methods that are described in theart or generally accepted by the practice of pharmaceutical industry.The Novaferon-containing preparations/formulations could also be made byusing the non-conventional methods, materials that have not beendescribed in the art nor used by the pharmaceutical industry.

For instance, parenteral formulations are usually injectable fluids thatconsist of the pharmaceutically and physiologically acceptable materialssuch as water, physiological saline, other balanced salt solutions,aqueous dextrose, glycerol, etc. In addition, the injectable fluidscould also contain, in addition to the Novaferon protein, other proteinsas carriers, such as human serum albumin or plasma preparations. Thepharmaceutical preparations/formulations may also contain minor amountsof non-toxic auxiliary substances, such as wetting or emulsifyingagents, preservatives, and pH buffering agents (for example sodiumacetate or sorbitan monolaurate). Methods of formulation are well knownin the art and are disclosed, for example, in Remington: The science andPractice of Pharmacy. Pharmaceutical Sciences (75).

The particular Novaferon protein preparations/formulations would bedetermined by the intended clinical applications and/or administrationmethods, and could be made by any one skilled in the art using knowntechniques. For instance, in addition to injectable fluids, topical andoral formulations can be employed. Topical preparations can include butare not limited to eye drops, ointments, and sprays. Oral formulationsinclude but are not limited to the forms of liquid (e.g., syrups,solutions or suspensions), or solid (e.g., powders, pills, tablets, orcapsules). For solid preparation/formulations, conventional non-toxicsolid carriers include but are not limited to the pharmaceutical gradesof mannitol, lactose, starch, or magnesium stearate. Actual proceduresand/or methods of making these preparations/formulations are known, orwill be apparent, to those skilled in the art (75).

The pharmaceutically acceptable preparations/formulations of theNovaferon protein can be administrated to humans and/or non-humanspecies in a variety of ways that include but are not limited to, oral,subcutaneous, intravenous, intranasal, transdermal, intraperitoneal,intramuscular, intrapulmonary, vaginal, rectal, or intraocular delivery,and in the treatment of wounds, directly applied locally.

The concentrations/amounts of the Novaferon protein in thepreparations/formulations may vary from >0 to 1.0 molar and/or >0 to100% (weight/weight) depending on the clinical practice. The exactdoses, administration intervals, and the duration of treatment of eachand/or all of the Novaferon preparations/formulations will be determinedby clinical trials, disease conditions, patient status and health careproviders. In a preferred embodiment, due to the protein degradation,systemic versus localized delivery, and rate of new protease synthesis,as well as the age, body weight, general health, sex, diet, time ofadministration, drug interaction and the severity of the condition,etc., adjustments to the Novaferon administration including but beingnot limited to the individual and/or total doses, administrationintervals, the duration of treatment, and necessary courses oftreatment, may be necessary, and will be ascertainable with routineexperimentation by those skilled in the art.

In a preferred embodiment, the in circulation half-life of Novaferonprotein after administration to the bodies of humans and/or non-humanspecies can be altered. The alternations include but are not limited tothe extension or shortening of Novaferon's half-life in vivo. Theextension of the in vivo half-life of the Novaferon protein can beachieved in various ways, which include but are not limited to:

-   -   (1). Complex formation between a Novaferon molecule and a        monoclonal antibody. Such an antibody would preferably connect        to the Novaferon protein at sites that do not materially impair        its therapeutic functions (103).    -   (2). Fusion complex of Novaferon with other        proteins/polypeptides. Novaferon molecule can be recombinantly        fused to other proteins/polypeptides, such as a fragment of the        constant region of an immunoglobin (Fc) (104).    -   (3) Conjugation of Novaferon protein. For example, Novaferon        protein can be conjugated with non-antigenic polymers, such as        polyethylene glycol or related polyalkylene glycol moieties        (105-108).

In another preferred embodiment, a therapeutic compound could beconjugated to an antibody, preferably an anti-Novaferon proteinantibody. The therapeutic compound may be a cytotoxic agent. In thismethod, the cytotoxic agents may be targeted, by the binding of theconjugated antibody to Novaferon molecules, to tumor tissue or cells,thereby destroying and the reducing the number of afflicted cells toachieve reduction of cancer symptoms. Cytotoxic agents include, but arenot limited to, cytotoxic drugs, toxins or active fragments of suchtoxins, and radiochemicals. Suitable toxins and their correspondingfragments include diptheria A chain, exotoxin A chain, ricin A chain,abrin A chain, curcin, crotin, phenomycin, enomycin and the like.

In a preferred embodiment, the full length sequence, partial sequences,and/or regulatory sequence of the Novaferon protein-encodingpolynucleotide sequence (SEQ ID No: 1) can be used in genetherapy-related administration by anyone skilled in the art. Theantisense application, based on the Novaferon protein-encodingpolynucleotide sequence (SEQ ID No: 1) can also be used either as genetherapy (i.e. for incorporation into the genome) or as antisensecompositions, as will be appreciated by those skilled in the art.

In gene therapy applications, genes are introduced into cells to achievethe in vivo synthesis of the target proteins encoded by these genes.Conventional gene therapy achieves the sustained therapeutic effects bya single treatment or repeated administration of a therapeuticallyeffective DNA or mRNA. On the other hand, antisense RNAs and DNAs canalso be used as therapeutic agents for blocking the expression ofcertain genes in vivo. It has already been shown that short antisenseoligonucleotides can be delivered into cells where they act asinhibitors (109).

In a preferred embodiment, the Novaferon protein-encoding polynucleotidesequence (SEQ ID No: 1), in full length or partial length, can be usedas DNA vaccines. Naked DNA vaccines are generally known in the art(110). Methods for the applications of the Novaferon-encoding gene (SEQID No: 1), full length or partial length, as DNA vaccines are well knownto one with ordinary skill in the art, and include but are not limitedto placing the Novaferon gene or portion of the Novaferon gene under thecontrol of a promoter for the expression of the full length or partiallength of the Novaferon protein in humans and/or non-human species.

EXAMPLES

The following examples serve to more fully describe the manner of usingthe above described invention, as well as to set forth the best modescontemplated for carrying out various aspects of the invention. It isunderstood that these examples in no way serve to limit the true scopeof this invention, but rather are presented for illustrative purposes.All references cited herein are expressly incorporated by reference intheir entirety.

Example 1 PCR Amplification of Human IFN-α Genes from Human LeukocytecDNAs

Total mRNA was extracted from human peripheral blood leukocytes.Preparation of cDNA was preformed using Advantage™ RT-for-PCR Kit(Clontech, Mountain View, Calif., US) and a cDNA synthesis primer (oligodT18) according to the manufacturer's recommendations.

Amplification of human IFN-α cDNAs was done by PCR technology on a MJPTC thermal cycler, using the following conditions: 2.5 μl 10×pfxamplification buffer (Invitrogen, Carlsbad, Calif., US), 0.75 μl 10 mMdNTPs, 0.5 μl 25 mM MgSO₄, 0.25 μl Platinum pfx DNA Polymerase (2.5U/μl; Invitrogen, Carlsbad, Calif., US), 0.75 μl cDNA, 0.75 μl 5′ primer(10 μM; IFNaO5: 5′-TGGTGCTCAGCT (A/G)CAAGTC-3′), (SEQ ID No:3) 0.75 μl3′ primer mixture (1.7 μM each;

IFNaO3-1: (SEQ ID No: 4) 5′-AATCATTTCCATGTTG(A/G)ACCAG-3′; IFNaO3-2:(SEQ ID No: 5) 5′-AATCATTTCCCGGTTGTACCAG-3′; IFNaO3-3: (SEQ ID No: 6)5′-AATCATTTCCATGTTGAAACAG-3′; IFNaO3-4: (SEQ ID No: 7)5′-AATCATTTCAAGATGAGCCCAG-3′; IFNaO3-5: (SEQ ID No: 8)5′-AATGATTTTCATGTTGAACCAG-3′; IFNaO3-6: (SEQ ID No: 9)5′-AATCATTT(C/G)(C/G)ATGTTGAACCAG-3′; IFNaO3-7: (SEQ ID No: 10)5′-GATCATTTCCATGTTGAATGAG-3′; IFNaO3-8: (SEQ ID No: 11)5′-GAGTCGTTTCTGTGTTGGATCAG-3′.

Amplified PCR products were electrophoresed on a 1.0% agarose gel,excised, gel-purified, and were cloned into pCRII-TOPO or pCR-4-TOPOvector (Invitrogen, Carlsbad, Calif., US) according to themanufacturer's recommendations. Automated sequencing was carried out ona Prism Ready Reaction Dye Termination mix on an ABI automated sequencer(PE Applied Biosystems, CA, US).

Since no desired inserts for the IFNa6, IFNa7 and IFNa16 codingsequences were found in above clones, PCRs were conducted again underthe above conditions with the exception of type specific primers. Forspecific amplification of IFNa6, 5′ and 3′ primers were 1FNaO5:5′-TGGTGCTCAGCT (A/G)CAAGTC-3′(SEQ ID No:3), and IFNaO3-8:5′-GAGTCGTTTCTGTGTTGGATCAG-3′(SEQ ID No:11) respectively. For specificamplification of IFNa7, 5′ and 3′ primers were IFNa7UO:5′-ATGCCCCTGTCCTTTTCTTTAC-3′(SEQ ID No:12) and an equal molar mix ofIFNaO3-5 and IFNaO3-6, respectively. For specific amplification ofIFNa16, 5′ and 3′ primers used were IFNa7UO and IFNaO3-7:5″-GATCATTTCCATGTTGAATGAG-3′(SEQ ID No:10) respectively. Amplifiedfragments were cloned into pCRII-TOPO or pCR-4-TOPO vector and sequencedas above.

All cloned Type I human IFN-alpha genes were individually aligned withthose DNA sequences in Genebank. The GeneBank nucleotide accessionnumbers for these genes referenced herein are: NM_(—)024013(IFN-α1),NM_(—)000605 (IFN-α2), NM_(—)010504 (IFN-α4), NM_(—)010505 (IFN-α5),NM_(—)008335 (IFN-α6), NM_(—)008334 (IFN-α7), NM_(—)008336 (IFN-α8),NM_(—)002171 (IFN-α10), NM_(—)002172 (IFN-α14), NM_(—)002173 (IFN-α16),NM_(—)021268 (IFN-α17), NM_(—)002175 (IFN-α21).

Example 2 Construction of Shuffling Libraries of Type I HuIFN-BearingPlasmids

To construct plasmids bearing the coding sequence of one of the Type Ihuman IFN-αs, 15 pairs of oligonucleotides, with BamHI and EcoRIrestriction sites, were synthesized (Genentech, South San Francisco,Calif., US), based on the individual cDNA coding region for mature humanType I IFN proteins. The GeneBank nucleotide accession numbers for theseproteins referenced herein are: NM_(—)024013(IFN-α1), NM_(—)000605(IFN-α2), NM_(—)010504 (IFN-α4), NM_(—)010505 (IFN-α5), NM_(—)008335(IFN-α6), NM_(—)008334 (IFN-α7), NM_(—)008336 (IFN-α8), NM_(—)002171(IFN-α10), NM_(—)002172 (IFN-α14), NM_(—)002173 (IFN-α16), NM_(—)021268(IFN-α17), NM_(—)002175 (IFN α21). The primers and plasmids constructedin Example 1 as templates were used in a standard PCR (111). Theresulting products were cleaved with restriction endonucleases (REs)BamHI and EcoRI and cloned into the E. coli expression vector pBVB,which is a derivate expression plasmid of pBV220 (86) containing a BamHIsite and an EcoRI site in its multiple cloning region. These finalconstructs were all verified by DNA sequence analysis (PE AppliedBiosystems, US).

DNA fragments containing human IFN ORF were amplified by PCR using apair of oligonucleotides, BVF4: 5′-AGGGCAGCATTCAAAGCAG-3′(SEQ ID No:13)and BVR3: 5′-TCAGACCGCTTCTGCGTTCTG-3′ (SEQ ID No:14), and by using TypeI HuIFN-bearing plasmids constructed previously. The resulting productswere mixed in equal amounts and subjected to DNase I digestion and PCRassembly according to the procedure described by Stemmer (112).

The assembled PCR products were further amplified by a pair of innerprimers: BVF: 5′-GAAGGCTTTGGGGTGTGTG-3′(SEQ ID No:15) and BVR:5′-AATCTTCTCTCATCCGC-3′(SEQ ID No:16), followed by BamHI and EcoRIdigestion and cloned back into the E. coli expression vector pBVBcleaved with REs BamHI and EcoRI. These final constructs were allverified by DNA sequence analysis. The plasmid-bearing shuffled HuIFN-αgenes were transformed into E. coli DH5α competent cells.

In all PCR procedures above, either PCR amplification or PCR assembly,regular DNA polymerase (New England Biolab, MA, US), instead of highfidelity DNA polymerase, was used.

Example 3 Screening the Shuffling Libraries

Freshly transformed E. coli DH5α cells were grown overnight on an LBplate at 37° C. Single colonies were individually picked up andinoculated in 100 μl of LB medium containing 50 μg/ml of ampicillin in96-well plates. Colonies were shaken at 250 rpm at 30° C. After beingcultured overnight, 10 μl of bacterial cultures were duplicatelyinoculated into 100 μl of LB medium containing 50 μg/ml of ampicillin in96-well plates. The original plates (so called stock plates) weretemporarily stored at 4° C. The cells in duplicated plates were grown at30° C. until OD600 became 0.4 and were then induced by 42° C. After4-hour's heat induction, bacteria cultures were directly moved into −80°C. freezer for starting the frozen-thaw cycle. After 2 cycles offrozen-thaw, the bacteria suspension/lysate was diluted to a desiredconcentration and exposed onto Daudi cell culture for ananti-proliferation test (101) or Wish cell culture for an anti-viraltest (113).

In each round of screening steps, 20,000 colonies were primarilyscreened and about 100 colonies with the highest anti-proliferative oranti-viral activities were selected for further confirmative testing.The selected bacterial cultures in stock plates were streaked on LBplates containing 50 μg/ml ampicillin. Single colonies were grownovernight at 37° C., picked, and inoculated in 1 ml of LB mediumcontaining 50 μg/ml of ampicillin in test tubes. Bacteria in tubes weregrown overnight at 30° C. with shaking at 250 rpm. Then 40 μl of grownbacteria was inoculated into one of another set of tubes containing 1 mlof LB with ampicillin (50 μg/ml). The samples were then subjected to thesteps of induction expression, cell culture harvesting, freeze-thawcycle treatment and anti-proliferative or anti-viral testing asdescribed above in regard to the primary screening steps.

In each round of screening steps, about 20 colonies with the highestanti-proliferative or anti-viral activity were chosen after confirmativetesting to make plasmids and their inserts were sequenced automatically.The inserts having a unique DNA sequence were further amplified by usinga pair of PCR primers BVBF: 5′-ACCATGAAGGTGACGCTC-3′(SEQ ID No:17); andBVR: 5′-AATCTTCTCTCATCCGC-3′(SEQ ID No:16), which are flanking sequencesat upstream and downstream of multiple cloning sites of pBVB vectorrespectively. The amplified PCR products were used for the next round ofshuffling library construction.

Five cycles of screening steps were performed based on the augment ofeither anti-proliferative or anti-viral activity.

Example 4 Expression and Purification of Recombinant Novaferon Proteinin E. coli

Novaferon protein (SEQ ID No:2) was expressed in E. coli. The readingframe of SEQ ID No: 1 with an artificial addition of initiation codonATG was cloned into the temperature-inducible pBVB vector under controlof the λPRPL promoter (114). The expression plasmid of Novaferon,pBVBNF, was transformed in DH5α cells. Single colonies were individuallypicked up and inoculated in 2 ml of LB medium containing 50 μg/ml ofampicillin and incubated at 30° C. for 8 hours. Then the 2 ml ofcultured bacteria was further incubated with 50 ml of medium containing50 μg/ml of ampicillin overnight at 30° C. with agitation. Next morning,the overnightly-cultured bacteria was seeded at a ratio of 1:10-1:20into a large volume of LB medium containing 50 μg/ml of ampicillin, andincubated at 30° C. with agitation. When the cultures had reached themid-log phase of growth (A550=0.5-0.6), the incubation temperature wasrapidly raised up to 42° C. and kept for 4 hours in order to induce theexpression of Novaferon. After 4-hour heat induction, the bacteria cellswere centrifuged and washed with PBS (137 mM NaCl, 2.7 mM KCl, 10 mMNa₂HPO₄, 2 mM KH₂PO₄) 3 times, then stored at −80° C. until proceedingto purification.

Most Novaferon protein molecules were soluble in the E. coli productionsystem described herein, although they were over-expressed in thecytoplasm. Thus, cells were disrupted by lysozyme digestion in CellLysis buffer I (50 mM Tris-Cl (pH8.0), 1 mM EDTA (pH8.0), 100 mM NaCl)(115). The lysate was further sonicated in order to disrupt theremaining intact cells and splice DNA molecules. Then the lysate wascentrifuged.

The soluble Novaferon protein molecules in the supernatants weresequentially purified by hydrophobic, ion exchange chromatography andgel filtration. First, the supernatants were loaded onto and passedthrough the Phenyl Sepharose 6 Fast Flow Column (GE Healthcare, US).Secondly, the fractions containing Novaferon protein were applied toPOROS 50 D Column (Applied Biosystems, US). Thirdly, the fractionscontaining Novaferon molecules were subject to the purification by POROS50 HSColumn (Applied Biosystems, US), and finally, the collectedNovaferon molecules were further purified by HiLoad 26/100 Superdex 75pg (Amersham, US).

The purity of the pure Novaferon protein was verified by 15% SDS-PAGEanalysis. The pure recombinant Novaferon protein showed as a single bandwith a molecular weight (MW) of 19-20 KDa. Mass spectrometry analysisindicated that the purity of the purified Novaferon molecule was >98%,and the molecular weight was 19313 dalton, which was identical with thepredicted molecular weight 19315 dalton from its amino acid sequence.

Example 5 Expression and Purification of Recombinant HuIFN-α2b in E.coli

The expression plasmid of HuIFN-α2b, pBV2b, contains the cDNA codingregion for the mature protein of HuIFN-α2b (GeneBank nucleotideaccession number: NM_(—)000605), which is under the control of theheat-inducible λ PRPL promoter. The expression of HuIFN-α2b wasperformed by following the protocols described by Joseph S and David W R(116).

The expression plasmid, pBV2bF, was transformed in DH5-α cells. Singlecolonies were individually picked up and inoculated in 2 ml of LB mediumcontaining 50 μg/ml of ampicillin and incubated 30° C. for 8 hours. Thenthe 2 ml of cultured bacteria was further incubated with 50 ml of mediumcontaining 50 μg/ml of ampicillin overnight at 30° C. with agitation.Next morning, the bacteria culture was seeded at a ratio of 1:10˜1:20into a large volume of LB medium containing 50 μg/ml of ampicillin, andincubated at 30° C. with agitation. When the cultures had reached themid-log phase of growth (A550=0.5-0.6), the incubation temperature wasrapidly raised up to 42° C. and kept for 4 hours in order to induce theexpression of HuIFN-α2b. After 4-hour's heat induction, the cells werecentrifuged and washed with PBS (137 mM NaCl, 2.7 mM KCl, 10 mM Na₂HPO₄,2 mM KH₂PO₄) 3 times, then stored at −80° C. until proceeding topurification.

HuIFN-α2b protein was insolubly expressed in the E. coli expressionsystem described herein, and thus the inclusion body recovery andwashing procedures were conducted according to protocols described inMolecular Cloning (115). Briefly, the harvested bacterial cells wereresuspended in Cell Lysis buffer I (50 mM Tris-Cl (pH8.0), 1 mM EDTA(pH8.0), 100 mM NaCl) and lysed by lysozyme and sonication. Inclusionbodies were washed 3 times with ice cold Cell Lysis buffer II (celllysis buffer I supplemented with 0.5% (v/v) Triton X-100).

Recovered inclusion bodies were broken by suspending in 7N guanidine atroom temperature with agitation for 4 hours. Following a 15 minutecentrifugation at 4° C., the denatured protein was refolded in 0.15 MpH9.5 Borex buffer for 48 hours at 4° C. The pH was adjusted to 7.4 byHCl at the last step of refolding.

The solution containing refolded HuIFN-α 2b was then purified byhydrophobic, ion exchange chromatography and gel filtration. First, thesolution was loaded onto and passed through the Phenyl Sepharose 6 FastFlow Column (GE Healthcare, US). Secondly, the fractions containingHuIFN-α2b were applied to POROS 50 D Column (Applied Biosystems, US).Thirdly, the fractions containing HuIFN-α2b were subject to thepurification by POROS 50 HSColumn (Applied Biosystems, US). Finally, thecollected HuIFN-α 2b molecules were further purified by HiLoad 26/100Superdex 75 pg (Amersham, US). The pure HuIFN-α2b protein showed as asingle band by 15% SDS-PAGE analysis and its purity was >98% asconfirmed by Mass spectrometry.

Example 6 Determination of Anti-Viral Activity of Novaferon

Anti-viral activity was determined using the WISH-VSV system asdescribed in the classical protocols described by Armstrong J A (113).On the first day, WISH cells (ATCC, catalog No. CCL 25) were seeded in96-well plates at a density of 14,000 cells/well and incubated at 37° C.24 hours later, 2-fold serial diluted Novaferon, HuIFN-α2b, WHO humanIFN international standards or blank culture medium was added into eachwell, and incubated at 37° C. for another 24 hours. On the third day,the medium was removed, and replaced with medium containing 1,000 PFU ofVesicular Stomatitis Virus (VSV, ATCC, catalog No. VR-1421). The cellswere again incubated for 24 hours at 37° C. and were then washed with0.85% NaCl to remove dead cells. Next, culture plates were soaked intodye-fixer solution (0.5% crystal violet, 5% formalin (V/V), 50% ethanol(V/V), and 0.85% NaCL) for 1 hour. The dye-fixer solution was thendecanted, and the microplates were rinsed copiously with tap water andallowed to dry. The stained cells were dissolved by 0.2 ml of2-methoxyethanol. The plates were read at 550 nm in a Model Opsys MR(Thermo Labsystems, US) for crystal violet bioassay.

All experiments were preformed in triplicate and the Novaferon andHuIFN-α2b samples were tested in the same plate. The anti-viralactivities of Novaferon and HuIFN-α2b prepared herein were assayed inparallel and the anti-viral units (international unit, or IU) weredetermined with reference to WHO international standards, 94/786(rHuIFN-α consensus) and 95/650 (rHuIFN-α2a), which were purchased fromNational Institute for Biological Standards and Control (NIBSC, USA).

The measured anti-viral activity of purified Novaferon protein againstVSV on WISH was 2.5×10⁹ IU/mg while the anti-viral activity of HuIFN-α2bis 2.0×10⁸ IU/mg. This data indicates that the anti-viral activity ofthe Novaferon protein is about 12.5-fold stronger than that ofHuIFN-α2b.

Example 7 Anti-Proliferative Activity of Novaferon

The anti-proliferative activity assay was performed basically asdescribed by Evinger and Pestka (101).

A. Cell Culture of Human Tumor Cell Lines

The human tumor cell lines were purchased from different organizations(Table 1, below), namely, ATCC (American Type Culture Collection, P.O.Box 1549, Manassas, Va. 20108, USA), DSMZ (German National ResourceCentre for Biological Material, Deutsche Sammlung von Mikroorganismenand Zellkulturen GmbH, Mascheroder Weg 1b, 38124 Braunschweig, Germany),JCRB (Japanese Collection of Research Bioresources-Cell Bank, NationalInstitute of Biomedial Innovation, 7-6-8 Saito-Asagi, Ibaraki-shi, Osaka567-0085, Japan).

TABLE 1 Human Tumor Cell Lines Cell lines Tumors Codes Organizations*A-375 Melanoma CRL1619 ATCC IGR-1 Melanoma Acc 236 DSMZ IGR-37 MelanomaAcc 237 DSMZ IPC-298 Melanoma Acc 251 DSMZ HCT-8 Colorectaladenocarcinoma CCL-244 ATCC SW1116 Colorectal adenocarcinoma CCL-233ATCC LS 180 Colorectal adenocarcinoma CL-187 ATCC DLD-1 Colorectaladenocarcinoma CCL-221 ATCC LS174T Colorectal adenocarcinoma CL-188 ATCCHep G2 hepatocellular carcinoma HB-8065 ATCC Hep3B hepatocellularcarcinoma HB-8064 ATCC HuH-7 Hepatoma 0403 JCRB PLC/PRF/5 HepatomaCRL-8024 ATCC HL60(S) lymphocytic 0163 JCRB Daudi Burkitt's lymphomaCCL-213 ATCC L-428 Hodgkin's lymphoma Acc 197 DSMZ DU 145 Prostatecarcinoma HTB-81 ATCC PC-3 Prostate carcinoma Acc 465 DSMZ MKN 1 Gastricadenocarcinoma 0252 JCRB KYSE 30 Esophagus carcinoma 0188 JCRB A549 Lungcarcinoma CCL-185 ATCC HeLa Cervix adenocarcinoma CCL-2 ATCC C-33ACervix carcinoma HTB-31 ATCC *DSMZ: German National Resource Centre forBiological Material (Deutsche Sammlung von Mikroorganismen undZellkulturen) Germany ATCC: American Type Culture Collection, USA JCRB:Japanese Collection of Research Bioresources-Cell Bank, Japan

All cells used in anti-proliferative activity test were cultured at 37°C. in a humidified atmosphere containing 5% CO₂. Cells were grownaccording to the growth manual of each cell, in basal growth media, suchas DMEM, MEM, F12K andl 640 or 1640 plus F12 (all from Gibco BRL, US),supplemented with 5-20% heat-inactivated fetal bovine serum FBS, fromGibco BRL, US. The basal growth media for each individual cell line islisted in Table 2, below. All cell lines were examined daily in cultureplates under an inverted microscope. Cells were harvested and used forexperiments in their logarithmic growth phase with viabilities exceeding90% as determined by trypan blue dye exclusion. The cell counts andviabilities were examined in standard hematocytometer.

TABLE 2 Culturing and Measuring Methods of Human Tumor Cell Lines Cellline Culture media Cells/Well Measure methods IGR-1 DMEM 5000 crystalviolet bioassay IGR-37 DMEM 2000 crystal violet bioassay IPC-298 16402000 crystal violet bioassay HCT-8 1640 500 crystal violet bioassay LS180 MEM 3000 crystal violet bioassay DLD-1 1640 1500 crystal violetbioassay Hep G2 MEM 1000 crystal violet bioassay Hep 3B MEM 800 crystalviolet bioassay HuH-7 DMEM 4000 crystal violet bioassay PLC/PRF/5 MEM6000 crystal violet bioassay KYSE 30 1640 + F12 1000 crystal violetbioassay DU 145 MEM 1000 crystal violet bioassay PC-3 1640 2000 crystalviolet bioassay MKN 1 1640 2000 crystal violet bioassay A549 F12K 400crystal violet bioassay SW 1116 1640 1000 crystal violet bioassay LS174TMEM 4000 crystal violet bioassay HeLa MEM 500 crystal violet bioassayC-33A MEM 1000 crystal violet bioassay A-375 DMEM 200 crystal violetbioassay HL 60(S) 1640 800 direct cell counting Daudi 1640 400 directcell counting L-428 1640 800 direct cell countingB. Procedure for Anti-Proliferative Assay

The cell lines with logarithmic growth phase were gently suspended inwarmed (36° C.) media to a density of 2×10³-6×10⁴ cells/ml (varying withcell line, see Table 2). 100 μl of cell suspension was seeded into eachwell of 96-well plate, followed by incubating for 6-8 hours at 37° C.Then equal volumes (100 μl) of Novaferon or HuIFN-α2b diluted in culturemedium was added to the wells in triplicate. The plates were agitatedgently for 4-5 seconds to mix the contents, and incubated at 37° C. for6 days. The Novaferon and HuIFN-α2b samples were tested in the sameplate in order to guarantee the comparability.

Two methods were used to determine the cell numbers in a cell well andto calculate the anti-proliferative activities of Novaferon andHuIFN-α2b according to the cell numbers.

A direct cell counting method was used to determine the cell number ofsuspension cell. After 6 days of culturing, suspension cell cultureswere diluted with trypan blue (final concentration: 0.02%), and cellnumbers were directly counted using hematocytometer.

Crystal violet bioassay method was used to determine the cell numbers ofthe adhesive cells (93). After 6 days of culturing, dead cells wereremoved by pipetting PBS up and down in the culture wells. Next, wellswere filled with dye-fixer solution to stain the live cells for 1 hour.The dye-fixer solution contained 0.5% crystal violet, 5% formalin (V/V),50% ethanol (UV), and 0.85% NaCl in distilled water. Then microplateswere rinsed copiously with tap water and allowed to dry. The stainedcells were dissolved by 0.2 ml of 2-methoxyethanol. Optical density at550 nm (OD550) (Model Opsys plate reader, Thermo Labsystems, US) wasmeasured and used as the relative indicator of cell numbers.

The growth-inhibition rate was calculated by the following formula:inhibition rate %=(1−(E−B)/(C−B))×100, where E was the number of cellsor the value of OD₅₅₀ in Novaferon or HuIFN-α2b-treated wells at day 6;B was the number of cells or the value of OD₅₅₀ in a cell culture at day0; C was the number of cells or the value of OD₅₅₀ in untreated wells atday 6.

The inhibition rate was expressed in conjunction with the compoundconcentrations. The IC₅₀ of Novaferon or HuIFN-α2b was estimated byusing a range of sample concentrations. The data were fit to Sigmoidalcurve (117) with Hill slope one: Y=min+(Max−min)/(1+10^(IC₅₀−X)) where Xis the log concentrations of drug; Y is the inhibition rate; Min or Maxis the minimum or maximum inhibition rate plateau. The IC₅₀ of variouscompounds against a particular target can be compared, where a lowerIC₅₀ indicates a more potent compound.

The concentrations of Novaferon and HuIFN-α2b and the corresponding cellgrowth inhibition rates for Daudi cell line are presented in FIG. 4.Based on this data, the IC₅₀ of Novaferon and HuIFN-α2b to inhibit Daudicell growth were calculated as 0.0174 μmol and 6.9550 μmol. Thus theIC₅₀ of Novaferon is about 1/400 of that of HuIFN-α2b, representing anapproximately 400-fold increase of Novaferon's anti-proliferativepotency in comparison to HuIFN-α2b.

The anti-proliferative activities of Novaferon were assessed andcompared with those of HuIFN-α2b on 23 tumor cell lines, including 4cell lines derived from melanoma (A-375, IGR-1, IGR-37, IPC-298), 5colorectal adenocarcinoma cell lines (HCT-8, SW1116, LS180, DLD-1,LS174T), 4 liver cancer cell lines (Hep G2, Hep 3B, HuH-7, PLC/PRF/5), 3lymphoma cell lines (HL-60(S), Daudi, L-428), 2 prostate carcinoma celllines (DU 145, PC-3), 2 cervical cancer cell lines (HeLa, C-33A), 1gastric adenocarcinoma cell line (MKN 1), 1 lung carcinoma cell line (A549) and one esophagus cancer cell line (KYSE 30). Novaferon exhibitedmuch stronger anti-proliferative activities than those of HuIFN-α2bagainst all tested cancer cell lines. The extent of increase of thepotency varied in the different cancer cell lines, and ranged from 16 to1134 fold (Table 3, below).

TABLE 3 IC₅₀ values of Novaferon and HuIFN-α2b and the increased foldsof tumor cell inhibition by Novaferon over HuIFN-α2b. IC₅₀ (pmol) FoldCell lines HuIFN-α2b Novaferon (Novaferon/HuIFN-α2b) PLC/PRF/5 0.04070.0025 16 A549 4.27 0.2202 19 DU 145 0.1319 0.0036 36 HepG2 0.1718 0.00443 HuH-7 0.1474 0.0026 58 Hep3B 4.3934 0.0758 58 IPC-298 0.0516 0.000770 LS174T 0.0165 0.0002 74 IGR-37 0.6017 0.0055 109 PC-3 1.8777 0.0146128 HeLa 0.2364 0.0017 141 C-33A 2.5242 0.0176 143 MKN 1 0.233 0.0011207 HCT-8 2.9479 0.0139 212 SW 1116 0.2278 0.001 222 DLD-1 0.3977 0.0014282 HL-60(S) 0.5855 0.0019 306 LS 180 0.7579 0.0022 350 Daudi 6.9550.0174 400 KYSE 30 18.0134 0.0264 683 A-375 1.4134 0.0019 733 IGR-16.6718 0.0076 876 L-428 17.2789 0.0152 1134

Example 8 In Vivo Tumor Model Experiments

A. Cell Culture and in Vivo Human Tumor Xenograft Models

Colon cancer cell line (LS 180), melanoma cell line (A-375) and livercancer cell line (Hep G2) were obtained from the American Type CultureCollection (ATCC, Rockville, Md.). Prostate cancer cell line (PC-3) wasobtained from German National Resource Centre for Biological Material(DSMZ, Deutsche Sammlung von Mikroorganismen and Zellkulturen, Germany).Lymphocytic cell line (HL 60(s)) was purchased from Japanese Collectionof Research Bioresources Cell Bank (JCRB, Japan). All cells werecultured according to their instructions (see Table 1). Briefly, LS 180and Hep G2 were cultured in MEM medium. A-375 was cultured in DMEM. Bothmedia were supplemented with 10% fetal bovine serum (FBS), 2 mMglutamine, 100 U/ml of penicillin, 100 mg/ml of streptomycin, 0.1 mMnon-essential amino acids, and 1.0 mM sodium pyruvate. PC-3 and HL 60(S)cells were cultured in RPMI 1640, supplemented with 10% FBS, 100 U/ml ofpenicillin, and 100 mg/ml of streptomycin. All cells were maintained in5% CO₂ atmosphere at 37° C.

Human cancer xenograft models were established using the methodsdescribed by Beverly et al (118). Log phase growing cancer cells wereharvested from tissue culture plates, washed, and resuspended inphosphate-buffered saline (PBS, pH=7.5, 20 mM). Subcutaneous tumorxenografts were generated in 6-week-old athymic nude Balb/c mice byinjecting 6×10⁶ cells/0.3 ml (PC-3, HepG2), 4×10⁶ cells/0.3 ml (LS 180),2×10⁷ cells/0.3 ml (HL 60(s)) or 8×10⁶ cells/0.3 ml (A-375)subcutaneously on both sides in the flank region. For each in vivo tumormodel, on day 6 after the tumor cell inoculation, tumor bearing mice(tumor volume is about 100 mm³) were randomly divided into 7 or 8 groupswith equal numbers of animals in each group, and treatment wascommenced.

Novaferon and HuIFN-α2b were formulated with PBS solution. Dailysubcutaneous injection of PBS alone, various doses of Novaferon, orHuIFN-α2b lasted for 30 days in total (PC-3, HepG2, A-375), 28 days (LS180) or 21 days (HL 60(s)) from the day of grouping mice. For thetreatment of 5-FU, 30 mg/kg of 5-FU was i.v. administrated once everytwo days for a total of 5 times. The groups and treatment doses aresummarized below:

-   Group 1 (Control): PBS daily.-   Group 2 (low dose of Novaferon): 1.25 μg/kg daily.-   Group 3 (medium dose of Novaferon): 12.5 μg/kg daily.-   Group 4 (high dose of Novaferon): 125 μg/kg daily.-   Group 5 (low dose of HuIFN-α2b): 1.25 μg/kg daily.-   Group 6 (medium dose of HuIFN-α2b): 12.5 μg/kg daily.-   Group 7 (high dose of HuIFN-α2b): 125 μg/kg daily.-   Group 8 (5-FU): 30 mg/kg, i.v. administration once every 2 days for    5 times.

Once treatment commenced, tumors were measured with a caliper once aweek. The tumor volumes were calculated using the following formula:volume=0.5×(width)²×(length). Mice were sacrificed at the day oftreatment discontinuation (day 30 after commencement of the treatment).Solid tumors were isolated, photographed, and measured.

The growth inhibitory rate was calculated using the following formula:inhibitory rate=[1−T/C]×100%, where T is the average tumor weight inNovaferon-, HuIFN-α2b-, or 5-FU-treated groups; C is the average tumorweight in control group after treatment.

B. Human Prostate Cancer Xenograft Model

Prostate cancer PC-3 xenografts were treated with s.c. injection of1.25, 12.5 or 125 μg/kg of Novaferon for 30 days. Novaferon exhibitedstrong, dose-dependent inhibition of the PC-3 tumor growth (P<0.05). Asshown in FIG. 5 and Table 4, below, PC-3 tumor growth in Novaferontreated groups was greatly suppressed as compared with the control groupof PBS treatment. For example, the average weight of PC-3 xenografttumor mass in Novaferon-treated group (125 μg/kg), 0.091±0.081 g. wasvery significantly reduced as compared with control animals, 1.948±0.567g (P<0.001) (Table 4). In other words, 30-day treatment of 125 μg/kgachieved 95.3% inhibition of the PC-3 tumor growth (Table 4).

TABLE 4 Tumor weight and growth inhibition rates of human prostatecancer PC-3 xenografts treated with Novaferon and HuIFN-α2b (n = 10)Dose Tumor weight (g) Inhibition Group (μg/kg) (mean ± SD) rate (%)Control — 1.948 ± 0.567 — Novaferon 1.25 1.266 ± 0.457* 35.0 low dosageNovaferon 12.5 0.759 ± 0.574*** 61.0 medium dosage Novaferon 125 0.091 ±0.081***@@@ 95.3 high dosage HuIFN-α2b 1.25 1.284 ± 0.862 34.1 lowdosage HuIFN-α2b 12.5 0.790 ± 0.391*** 59.4 medium dosage HuIFN-α2b 1250.476 ± 0.271*** 75.6 high dosage note: *p < 0.05, ***p < 0.001:compared to control group; @@@p < 0.001: compared to HuIFN-α2b high dosegroup

Balb/c nude mice were treated with daily s.c. injection of Novaferon(1.25 μg/kg, 12.5 μg/kg or 125 μg/kg) for 30 days after 6×10⁶ live PC-3cells were introduced subcutaneously into mice. Results were expressedas average tumor volume (mm³). FIG. 5 showed that all three doses ofNovaferon exhibited dose-dependent inhibition of PC-3 tumor growth incomparison to the PBS control group (P<0.05). 125 μg/kg of Novaferoninduced much stronger, or almost complete, inhibition of PC-3 tumorgrowth than that of HuIFN-μ2b at the same dose (95.3% vs 75.6%, P<0.01)(Table 4).

It is interesting to notice that the longer treatment of Novaferon orHuIFN-α2b resulted in bigger differences in tumor growth inhibition inthe high dose (125 μg/kg)-treated groups. The average volume of PC-3tumor mass in the Novaferon-treated group was 107.9±68.7 mm³ versus620.7±296.6 mm³ in HuIFN-α2b-treated group at day 28 (P<0.001) and122.1±100.7 mm³ versus 691.9±428.3 mm³ at day 30 (P<0.001). This wasalso the case when the average tumor weight was considered after thetermination of the observation (0.091±0.081 g in Novaferon high dosagegroup versus 0.476±0.271 gram in HuIFN-α2b high dosage group, P<0.001).This suggested that longer treatment of Novaferon at this dose mayexhibit better or complete inhibition of PC-3 tumor growth in thisxenograft model.

C. Human Liver Cancer Xenograft Model

The in vivo anti-tumor activity of Novaferon was also evaluated on livercancer Hep G2 xenograft model. Novaferon exhibited effective,dose-dependent inhibition of Hep G2 tumor growth compared to controlgroup (P<0.001). The average tumor volumes in Novaferon-treated groups(daily s.c. injection of 1.25, 12.5 or 125 μg/kg for 30 days) were783.2±270.0, 459.3±414.3, and 104.6±56.5 mm³, respectively, incomparison with 2125.8±743.1 mm³ in PBS control group. 30-day treatmentof 125 μg/kg of Novaferon achieved the highest inhibition of the Hep G2(96.6%), which was significantly better than that by 125 μg/kg ofHuIFN-α2b (89.2%, P<0.01). Longer treatment of Novaferon at this doseshowed the trend of even better or complete inhibition. The averagetumor weight at the end of observation period was 0.074±0.083 g in 125μg/kg for the Novaferon-treated group, significantly less than that in125 μg/kg of HuIFN-α2b-treated group (0.235±0.199 gram, P<0.001) (Table5, below).

Balb/c nude mice were treated with daily s.c. injection of Novaferon(1.25 μg/kg, 12.5 μg/kg and 125 μg/kg) for 30 days after 6×10⁶ live HepG2 cells were introduced subcutaneously into mice. Results wereexpressed as average tumor volume (mm³). FIG. 6 showed that all threedoses of Novaferon exhibited dose-dependent inhibition of Hep G2 tumorgrowth in comparison to the PBS control group (P<0.001). 125 μg/kg ofNovaferon induced much stronger, or almost complete, inhibition of HepG2 tumor growth than that of HuIFN-α2b at the same dose (96.6% vs 89.2%,P<0.05) (Table 5).

TABLE 5 Tumor weight and growth inhibition rates of human liver cancercell Hep G2 xenografts treated with Novaferon and HuIFN-α2b (n = 10)Dose Tumor weight (g) Inhibition Group (μg/kg) (Mean ± SD) rate (%)Control — 2.179 ± 0.578 — Novaferon 1.25 0.797 ± 0.397*** 63.4 lowdosage Novaferon 12.5 0.321 ± 0.300*** 85.3 medium dosage Novaferon 1250.074 ± 0.083***@ 96.6 high dosage HuIFN-α2b 1.25 1.070 ± 0.587** 50.9low dosage HuIFN-α2b 12.5 0.531 ± 0.287*** 75.6 medium dosage HuIFN-α2b125 0.235 ± 0.199*** 89.2 high dosage Note: **p < 0.01, ***p < 0.001,compared to control group. @p < 0.01, compared with HuIFN-α2b highdosage groupD. Human Melanoma Xenograft Model

The in vivo anti-tumor activity of Novaferon was further evaluated inmalignant melanoma A-375 xenograft model. A-375 cell line (ATCC number:CRL-1619) was derived from a human malignant solid tumor. Novaferonexhibited effective, dose-dependent inhibition of A-375 tumor growthcompared to control group (P<0.001). The inhibition rates in theNovaferon-treated groups (daily s.c. injection of 1.25, 12.5 or 125μg/kg for 28 days) were 40.1%, 75.0% and 82.8% respectively, incomparison with PBS control group (P<0.001) (Table 6, below). 30-daytreatment of 125 μg/kg of Novaferon achieved the highest inhibition ofthe A-375 (82.8%), which was significantly better than that by 125 μg/kgof HuIFN-α1b (69.9%, P<0.001).

Interestingly, Novaferon exhibited more effective inhibition of thegrowth of melanoma cell A-375 than the chemotherapeutic agent, 5-FU(Table 6). On day 30, for instance, the mean tumor weights of in thegroups treated with 12.5 μg/kg or 125 μg/kg of Novaferon were0.763±0.187 (P<0.01) and 0.527±0.149 (P<0.001) grams, whereas the meantumor weight for the group treated with 5-FU, 30 mg/kg, was 1.004±0.105gram (Table 6). This indicates that Novaferon may be more effective forthe treatment of human melanoma A-375 than 5-FU.

Balb/c nude mice were treated with the daily s.c. injection of Novaferon(1.25 μg/kg, 12.5 μg/kg and 125 μg/kg) for 28 days after 8×10⁶ A-375cells were introduced subcutaneously into mice. Results are expressed asaverage tumor volume (mm³). FIG. 7 showed that all three doses ofNovaferon exhibited dose-dependent inhibition of A-375 tumor growth incomparison to the PBS control group (P<0.001). 125 μg/kg of Novaferoninduced stronger inhibition of A-375 tumor growth than that by HuIFN-α2bat the same dose (82.8% vs 69.9%, P<0.001) (FIG. 7). Both 12.5 μg/kg and125 μg/kg of Novaferon showed better suppression (75.0% and 82.8%respectively) of the tumor growth than by 5-FU (67.2%, P<0.01 andP<0.001) (FIG. 7).

TABLE 6 Tumor weight and growth inhibition rates of human melanoma cellA-375 xenografts treated with Novaferon and HuIFN-α2b (n = 10) DoseTumor weight (g) Inhibition Group (μg/kg) (X ± SD) rate (%) Control —3.057 ± 0.384 — Novaferon 1.25 1.830 ± 0.289*** 40.1 low dosageNovaferon 12.5 0.763 ± 0.187***&&$$$ 75.0 medium Novaferon 125 0.527 ±0.149***&&&@@@ 82.8 high dosage HuIFN-α2b 1.25 1.890 ± 0.148*** 38.2 lowdosage HuIFN-α2b 12.5 1.681 ± 0.132*** 45.0 medium HuIFN-α2b 125 0.920 ±0.139*** 69.9 high dosage 5-FU 30,000 1.004 ± 0.105*** 67.2 note: ***p <0.001, compared to control group; $$$p < 0.001, compared to HuIFN-α2bmedium dosage (12.5); @@@p < 0.001 compared to HuIFN-α2b high dosage(125) group; &&p < 0.01, &&&p < 0.001, compared to 5-FU groupE. Human Colon Cancer Xenograft Model

The in vivo anti-tumor activity of Novaferon was evaluated in coloncancer LS 180 xenograft model. LS 180 cell line (ATCC number: CL-187)was derived from a human colon adenocarcinoma. Novaferon exhibitedeffective, dose-dependent inhibition of colon cancer LS180 tumor growthcompared to control group (P<0.001). The inhibition rates in theNovaferon-treated groups (daily s.c. injection of 1.25, 12.5 or 125μg/kg for 28 days) were 75.0%, 80.5% and 92.5% respectively compared tothe PBS control group (P<0.001, Table 7, below). 28-day treatment of 125μg/kg of Novaferon achieved the highest inhibition of LS 180 tumorgrowth (92.5%), which was significantly better than that by 125 μg/kg ofHuIFN-α2b (82.3%, P<0.001).

Following 28-day treatment, 12.5 μg/kg of Novaferon inhibited the growthof LS 180 cancer xenografts similarly to 5-FU (30 mg/kg) in terms of theaverage tumor weights, (0.815±0.221 grams vs 0.758±0.227 grams). 125μg/kg of Novaferon inhibited the tumor growth of LS 180 significantlybetter than 30 mg/kg of 5-FU, (92.5% vs 81.8%, P<0.001) (Table 7 andFIG. 8). These observation was extremely interesting, considering theroutine clinical application of 5-FU in the standard chemotherapy topatients with colon cancer. The better suppression by Novaferon of LS180 tumor growth in animal model indicates that Novaferon has thepotential to work as a very effective anti-colon cancer agent in aclinical setting.

Balb/c nude mice were treated with a daily injection of Novaferon (1.25μg/kg, 12.5 μg/kg and 125 μg/kg) for 28 days after 4×10⁶ l LS 180 cellswere introduced subcutaneously into mice. Results were expressed asaverage tumor volume (mm³). FIG. 8 showed that all three doses ofNovaferon exhibited dose-dependent inhibition of LS180 tumor growth incomparison to the PBS control group (P<0.001). 125 μg/kg of Novaferoninduced stronger inhibition of LS 180 tumor growth than that byHuIFN-α2b at the same dose (92.5% vs 82.3%, P<0.001) (Table 7). Both1.25 μg/kg and 12.5 μg/kg of Novaferon achieved similar suppression(75.0% and 80.5% respectively) of the tumor growth in comparison to 5-FU(81.8%) (Table 7, FIG. 8). However, 125 μg/kg of Novaferon exhibitedmuch better inhibition of LS 180 tumor growth than that by 5-FU (92.5%vs 81.8%, P<0.001).

TABLE 7 Tumor weight and growth inhibition rates of human colon cancercell LS 180 xenografts treated with Novaferon and HuIFN-α2b (n = 10)Dose Tumor weight (g) Inhibition Group (μg/kg) (X ± SD) rate (%) Control— 4.170 ± 3.409 — Novaferon 1.25 1.043 ± 0.433*** 75.0 low dosageNovaferon 12.5 0.815 ± 0.221*** 80.5 medium dosage Novaferon 125 0.314 ±0.086***&&&@@@ 92.5 high dosage HuIFN-α2b 1.25 1.225 ± 0.565*** 70.6 lowdosage HuIFN-α2b 12.5 1.076 ± 0.442*** 74.2 medium HuIFN-α2b 125 0.740 ±0.310*** 82.3 high dosage 5-FU 30,000 0.758 ± 0.227*** 81.8 Note: ***p <0.001, compared to control group; @@@p < 0.001, compare to HuIFN-α2bhigh dosage; &&&p < 0.001, compare to 5-FU groupF. Human Leukemia Xenograft Model

The in vivo anti-tumor activity of Novaferon was also assessed in HL60(s) lymphocytic leukemia xenograft model. Novaferon exhibitedeffective, dose-dependent inhibition of HL 60(s) tumor growth comparedto control group (P<0.001). The inhibition rates in theNovaferon-treated groups (daily s.c. injection of 1.25, 12.5 or 125μg/kg for 28 days) were 43.8%, 55.2% and 80.4% respectively compared tothe PBS control group (P<0.001, Table 8, below). 21-day treatment of 125μg/kg of Novaferon achieved the highest inhibition of HL 60(s) tumorgrowth (80.4%), which was significantly better than that by 125 μg/kg ofHuIFN-γ2b (69.8%, P<0.05).

Balb/c mice were treated with the daily s.c. injection of Novaferon(1.25 μg/kg, 12.5 μg/kg and 125 μg/kg) for 21 days after 2×10⁷ live HL60(s) cells were introduced subcutaneously into mice. Results wereexpressed as average tumor volume (mm³). FIG. 9 showed that all threedoses of Novaferon exhibited dose-dependent inhibition of LS180 tumorgrowth in comparison to the PBS control group (P<0.001). 125 μg/kg ofNovaferon induced stronger inhibition of LS 180 tumor growth than thatby HuIFN-α2b at the same dose (80.4% vs 69.8%, P<0.05), and similarinhibition comparing to 5-FU (FIG. 9, Table 8).

TABLE 8 Tumor weight and growth inhibition rates of human leukemia CellLS 60(S) xenografts treated with Novaferon and HuIFN-α2b (n = 10) DoseTumor weight (g) Inhibition Group (μg/kg) (X ± SD) rate (%) Control —3.723 ± 0.750 — Novaferon 1.25 2.091 ± 0.653*** 43.8 low dosageNovaferon 12.5 1.668 ± 0.665*** 55.2 medium dosage Novaferon 125 0.729 ±0.332***@ 80.4 high dosage HuIFN-α2b 1.25 2.401 ± 0.698*** 35.5 lowdosage HuIFN-α2b 12.5 1.870 ± 0.660*** 49.8 medium dosage HuIFN-α2b 1251.124 ± 0.397*** 69.8 high dosage 5-FU 30,000 0.893 ± 0.289*** 76.0Note: ***p < 0.001, compared to control group; @p < 0.05, compared toHuIFN-α2b high dosage (125) groupG. General Condition of the Mice During Novaferon Treatment

The mice with the various xenografts of human cancers were closelyobserved during the period of Novaferon, HuIFN-α2b or 5-FU treatment.Unlike in the 5-Fu-treated groups, mice in all Novaferon- orHuIFN-α2b-treated groups generally ate and behaved normally, and had noweight loss. The 5-FU-treated mice showed typical changes of eating andbehavior, and weight loss. These observations indicate that whileshowing similar or better anti-cancer potency than 5-FU in the xenograftanimal models, Novaferon may be more specific toward the inhibition ofcancer cell and have much less effects on normal cells and/orphysiological functions. These may be translated into a better toleranceand superior therapeutic effects in human applications.

As will be apparent to those skilled in the art in the light of theforegoing disclosure, many alterations and modifications are possible inthe practice of the invention without departing from the spirit or scopethereof. Accordingly, the scope of the invention is to be construed inaccordance with the substance defined by the appended claims.

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What is claimed is:
 1. A protein exhibiting human interferon-likeanti-proliferative activity, wherein said protein comprises an aminoacid sequence at least 89% identical to SEQ ID NO:
 2. 2. The protein asdefined in claim 1, wherein said sequence is at least 90% identical toSEQ ID NO:
 2. 3. The protein as defined in claim 1, wherein saidsequence is at least 95% identical to SEQ ID NO:
 2. 4. The protein asdefined in claim 1, wherein said protein has anti-proliferative activityat least 10 fold greater than HuIFN-α2b.
 5. The protein as defined inclaim 4, wherein said protein has anti-proliferative activity at least50 fold greater than HuIFN-α2b.
 6. The protein as defined in claim 5,wherein said protein has anti-proliferative activity at least 100 foldgreater than HuIFN-α2b.
 7. The protein as defined in claim 6, whereinsaid protein has anti-proliferative activity at least 200 fold greaterthan HuIFN-α2b.
 8. The protein as defined in claim 1, wherein saidprotein is recombinantly produced.
 9. The protein as defined in claim 1,wherein said protein has a molecular weight of 19315 daltons.
 10. Theprotein as defined in claim 1, optionally comprising a methionineresidue at the N terminus.
 11. The protein as defined in claim 1,wherein said sequence is at least 93% identical to SEQ ID NO:
 2. 12. Theprotein as defined in claim 1, wherein said sequence is at least 96%identical to SEQ ID NO:
 2. 13. The protein as defined in claim 1,wherein said sequence is at least 97% identical to SEQ ID NO:
 2. 14. Theprotein as defined in claim 1, wherein said sequence is at least 98%identical to SEQ ID NO:
 2. 15. The protein as defined in claim 1,wherein said sequence is at least 99% identical to SEQ ID NO:
 2. 16. Theprotein as defined in claim 1, wherein said protein exhibits humaninterferon-like anti-viral activity.
 17. The protein as defined in claim16, wherein said protein has enhanced anti-viral and anti-proliferativeactivity in comparison to human interferon alpha 2b (HuIFN-α2b).
 18. Theprotein as defined in claim 17, wherein said protein has anti-viralactivity at least 2 fold greater than HuIFN-α2b.
 19. The protein asdefined in claim 18, wherein said protein has anti-viral activity atleast 5 fold greater than HuIFN-α2b.
 20. The protein as defined in claim19, wherein said protein has anti-viral activity at least 10 foldgreater than HuIFN-α2b.
 21. A composition comprising the protein asdefined in claim 1 and a pharmaceutically acceptable carrier, diluent orexcipient.
 22. A polypeptide comprising a fragment of the protein asdefined in claim 1, wherein said fragment comprises at least 148contiguous amino acids and exhibits anti-viral and anti-proliferativebiological activities at least as active as human interferon alpha 2b.23. A protein construct comprising the protein as defined in claim 1coupled to a moiety, wherein said construct exhibits said humaninterferon-like biological activities.
 24. The protein construct asdefined in claim 23, wherein said protein is glycosylated.
 25. Theprotein construct as defined in claim 23, wherein said moiety is apolypeptide.
 26. The protein construct as defined in claim 23, whereinsaid moiety is a non-polypeptide.
 27. The protein construct as definedin claim 26, wherein said moiety is a polymer molecule.
 28. The proteinconstruct as defined in claim 27, wherein said polymer molecule is alinear or branched polyethylene glycol.
 29. The protein construct asdefined in claim 23, wherein said moiety is a labeling molecule.
 30. Aprotein comprising a sequence which differs in 0 to 19 amino acids fromSEQ ID NO: 2, wherein said protein exhibits human interferon-likeanti-proliferative activity.
 31. The protein as defined in claim 30,wherein said protein exhibits human interferon-like anti-viral activity.32. The protein as defined in claim 31, wherein said protein hasenhanced anti-viral and anti-proliferative activity in comparison toHuIFN-α2b.
 33. The protein as defined in claim 32, wherein said proteinhas anti-viral activity at least 2 fold greater than HuIFN-α2b.
 34. Theprotein as defined in claim 30, wherein said protein hasanti-proliferative activity at least 10 fold greater than HuIFN-α2b. 35.The protein as defined in claim 34, wherein said protein hasanti-proliferative activity at least 100 fold greater than HuIFN-α2b.36. The protein as defined in claim 30, wherein said protein isrecombinantly produced.
 37. A composition comprising the protein asdefined in claim 30 and a pharmaceutically acceptable carrier, diluentor excipient.
 38. A protein exhibiting human interferon-like biologicalactivities, wherein said protein comprises an amino acid sequence atleast 95% identical to SEQ ID NO: 2 and wherein said protein hasenhanced anti-viral and anti-proliferative activities in comparison toHuIFN-α2b.
 39. A composition comprising the protein of claim
 38. 40. Aprotein having the amino acid sequence of SEQ ID NO: 2 or a fragmentthereof comprising at least 148 contiguous amino acids exhibiting humaninterferon-like biological activities.
 41. A protein exhibiting humaninterferon-like anti-proliferative biological activities, wherein saidprotein is selected from the group consisting of proteins eachcomprising an amino acid sequence at least 95% identical to SEQ ID NO:2.
 42. A composition comprising the protein as defined in claim 41 and apharmaceutically acceptable carrier, diluent or excipient.
 43. A proteincomprising a sequence which differs in 0 to 8 amino acids from SEQ IDNO: 2, wherein said protein exhibits human interferon-likeanti-proliferative biological activities.
 44. The protein as defined inclaim 43, wherein said protein exhibits human interferon-like anti-viralactivity.
 45. The protein as defined in claim 41, wherein said proteinexhibits human interferon-like anti-viral activity.
 46. A compositioncomprising the protein as defined in claim 43 and a pharmaceuticallyacceptable carrier, diluent or excipient.
 47. A protein exhibiting humaninterferon-like anti-viral activity, wherein said protein comprises anamino acid sequence at least 89% identical to SEQ ID NO:
 2. 48. Aprotein exhibiting human interferon-like biological activities, whereinsaid protein is selected from the group consisting of proteins eachcomprising an amino acid sequence at least 90% identical to SEQ ID NO:2, wherein the protein has anti-proliferative activity at least 10 foldgreater than human interferon alpha 2b (HuIFN-α2b.